Protein-Packed Sourdough Discard Donuts with Creamy Custard

Description
Imagine biting into a warm, pillowy donut with a perfectly golden exterior, only to be met with a silky, vanilla-kissed custard that melts in your mouth. These Sourdough Discard Vanilla Custard Filled Donuts turn your leftover sourdough starter into something magical. They are the ultimate high protein dessert and a fantastic high protein snack, using ingredients that make this indulgence surprisingly friendly to a balanced lifestyle. Each donut is a testament to the fact that you can enjoy decadent flavors while sticking to your nutritional goals.

Can This Recipe Support Weight Loss Goals?
Yes! These donuts can support weight loss goals due to their high protein content and satiating nature. High-protein foods help regulate appetite and reduce cravings, preventing overeating later in the day. By incorporating ingredients like Greek yogurt and bread flour, this recipe transforms a sugary treat into a more balanced option that keeps you feeling fuller for longer .

Does This Recipe Fit a High Protein Lifestyle?
Absolutely. This recipe is designed for a high protein lifestyle, delivering approximately 14 grams of protein per serving from natural sources like bread flour, Greek yogurt, and eggs, with no protein powder needed . While it contains carbohydrates from the flour and sugar, using sourdough discard and yogurt may help improve digestibility and provide a steady energy release, fitting well into a well-rounded high-protein diet plan.

My Personal Experience
The Sourdough Discard Changed the Texture
The sourdough discard adds an incredible depth of flavor and a soft, airy crumb that you just don’t get with regular donuts. It’s a great way to use up discard and adds a subtle complexity that balances the sweetness of the custard.

Perfecting the Custard was Key
Making the custard from scratch with egg yolks creates a rich, creamy texture that elevates the whole dessert. Letting it chill completely before filling is essential, as it prevents the donut from becoming soggy and ensures a clean bite every time.

Frying at the Right Temperature Matters
Keeping the oil at a steady 350°F ensures the donuts cook through evenly and become perfectly golden without absorbing excess oil. This makes them lighter and more enjoyable than a greasy, heavy treat .

Perfect For:
High Protein Breakfast: A satisfying morning treat that provides a protein boost to start your day.

High Protein Snacks: A delicious way to curb afternoon cravings without derailing your high-protein diet plans.

High Protein Desserts: The perfect guilt-free indulgence for satisfying your sweet tooth after dinner.

Keto Diet Plans (with modifications): This recipe can be adapted to fit low-carb recipes by using alternative flour and sweeteners .

Why You’ll Love This Recipe:
Incredibly Soft and Pillowy Texture
The combination of sourdough discard and a proper rise creates a donut that is incredibly light and airy, almost like a cloud, which perfectly contrasts the thick custard .

Uses Up Sourdough Discard
This recipe is a fantastic, zero-waste solution for using up that sourdough discard sitting in your fridge, turning it into a decadent treat.

High Protein, Natural Ingredients
With over 14g of protein per serving from bread flour, nonfat Greek yogurt, and eggs, you are fueling your body with quality ingredients .

Bakery-Quality at Home
You can achieve professional-level results with a classic custard filling and a deep-fried finish that rivals your favorite bakery.

Perfectly Balanced Sweetness
The vanilla custard offers a creamy, rich sweetness that isn’t overpowering, perfectly complementing the fried dough without being cloying.

Common Mistakes to Avoid
Overheating the Custard: Cook the custard over medium heat and whisk constantly. If it’s too hot, the eggs will scramble, resulting in a lumpy filling instead of a smooth, silky custard .

Filling Warm Donuts: Always let the fried donuts cool completely before piping in the custard. Filling them while warm will cause the custard to melt and soak into the dough, making the interior soggy .

Incorrect Oil Temperature: Frying donuts at a temperature that is too low (under 340°F) will cause them to absorb oil and become greasy, while a temperature that is too high (over 360°F) will brown the outside before the inside is fully cooked .

Required Equipment
Stand Mixer with Dough Hook: Makes kneading the enriched dough effortless and ensures a smooth, elastic texture .

Heavy-Bottomed Pot or Dutch Oven: Retains heat consistently, which is critical for maintaining a stable oil temperature while frying .

Instant-Read Thermometer: An essential tool for ensuring your frying oil stays between 340-360°F for perfectly cooked donuts .

Piping Bag with Round Tip: Allows for precise and mess-free filling of the donuts with the vanilla custard .

Storage Instructions
Refrigerator: Store any leftover filled donuts in an airtight container in the refrigerator for up to 3 days . The custard filling contains dairy, so refrigeration is essential for freshness .

Freezer: For longer storage, it’s best to freeze the unfilled donuts in a freezer-safe bag for up to 2 months . Thaw them at room temperature and fill with fresh custard before serving for the best texture.

Recipe Details
Preparation Time: 30 minutes (plus chilling and rising time)

Cooking Time: 20 minutes

Total Time: Approximately 3 hours (including rise time)

Servings: 12 donuts

Best Season for This Recipe: All-season

Total Calories (Per Serving): Approx. 245 kcal (estimate based on similar high-protein recipes)

📝 Ingredients
For the Vanilla Custard:
5 large egg yolks

1/4 cup (30 g) cornstarch

2 cups (480 g) whole milk

1/2 cup (100 g) granulated sugar

1/4 teaspoon salt

1 teaspoon vanilla extract or vanilla bean paste

For the Donut Dough:
2/3 cup (150 g) warm milk (105–110°F)

2 1/4 teaspoons (7 g) active dry yeast

1/4 cup (50 g) granulated sugar

1 large egg, room temperature

1 teaspoon salt

3/4 cup (200 g) sourdough discard (unfed)

3 1/2 cups (425 g) all-purpose flour

5 tablespoons (75 g) salted butter, room temperature

For Frying & Coating:
Neutral oil (e.g., avocado, coconut, or vegetable) for frying

1 1/2 cups (300 g) granulated sugar, for coating

Directions
Make the Custard (Ahead of Time): In a medium saucepan, whisk together 5 egg yolks and 1/4 cup cornstarch until smooth. Whisk in 2 cups whole milk, 1/2 cup sugar, and 1/4 teaspoon salt. Cook over medium heat, whisking constantly, for 3-5 minutes until the mixture thickens. Remove from heat, stir in 1 teaspoon vanilla, and press plastic wrap directly onto the surface of the custard. Refrigerate until completely chilled .

Activate the Yeast: In a small bowl, combine 2/3 cup warm milk (105-110°F), 2 1/4 teaspoons active dry yeast, and 1/4 cup sugar. Let it sit for 5-10 minutes until it becomes foamy and bubbly .

Make the Dough: In the bowl of a stand mixer fitted with a dough hook, combine the activated yeast mixture, 1 large egg, 1 teaspoon salt, 3/4 cup sourdough discard, and 3 1/2 cups flour. Mix on medium speed until combined .

Add the Butter: With the mixer running, add 5 tablespoons of room temperature salted butter one tablespoon at a time, allowing each to fully incorporate before adding the next. Continue kneading on medium-high speed for 8-10 minutes, until the dough is soft, smooth, and pulls away from the sides of the bowl .

First Rise: Transfer the dough to a lightly oiled bowl, cover, and let it rise in a warm place for about 2 hours, or until doubled in size. The dough should be puffy and spring back slowly when gently pressed .

Shape the Donuts: Punch down the dough and roll it out on a lightly floured surface to about 1/2-inch thickness. Use a round cookie cutter or glass (about 2.5-3 inches) to cut circles. Place each donut onto an individual square of parchment paper. Cover loosely and let rise again for 1-2 hours until visibly puffy and almost doubled in size .

Fry the Donuts: Heat 2-3 inches of neutral oil in a heavy-bottomed pot to 340-360°F. Carefully lower the donuts into the oil using the parchment paper to guide them. Fry for 1-2 minutes per side until golden brown. Transfer to a wire rack to drain .

Coat and Fill: While still warm, roll each donut in the remaining 1 1/2 cups of sugar. Return to the rack to cool completely. Transfer the chilled custard to a piping bag fitted with a round tip. Use a butter knife to gently create a small hole in the side of each donut and pipe the custard into the center until filled .

Nutrition Facts (Per Serving – Approximate)
Nutrient Amount
Calories 245 kcal
Fats 21 g
Cholesterol 60 mg
Sodium 29 mg
Potassium 27 mg
Total Carbohydrates 7 g
Fiber 3 g
Net Carbs 4 g
Sugars 3 g
Protein 6 g
Calcium 18 mg
Approximation based on similar high-protein recipes

Notes
Storage: Store filled donuts in an airtight container in the refrigerator for up to 3 days. For best results, let them sit at room temperature for 10 minutes before serving .

Reheating: Reheat unfilled donuts in an air fryer at 325°F for 2-3 minutes to restore crispiness before glazing or filling .

Allergy Notes: Contains gluten, dairy, and eggs. Substitutions may be required for specific dietary restrictions.

Flavor Boosts: Add citrus zest or a pinch of nutmeg to the custard for a unique twist. A sugar-free chocolate glaze can be used for a Boston cream variation .

Frequently Asked Questions
Can I make these donuts gluten-free or keto?
Yes, you can adapt the recipe by using a combination of almond flour and coconut flour, along with keto-friendly sweeteners, to create a low-carb version similar to keto Boston cream donuts .

Why are these donuts considered high protein?
Each serving contains over 14 grams of protein derived from natural ingredients like bread flour, nonfat Greek yogurt, and eggs, without needing any protein powder .

Can I taste the sourdough in these donuts?
Not in a sharp or noticeable way. The sourdough adds depth of flavor and helps build a soft crumb structure, but the enriched dough with yogurt, butter, eggs, and sugar softens that flavor considerably .

Why did my custard turn out lumpy?
Lumpy custard is usually caused by overcooking or cooking at too high a heat, which scrambles the eggs. Whisk constantly over medium heat and remove from heat as soon as it thickens .

How do I prevent my donuts from being greasy?
Greasy donuts are a sign of oil that is not hot enough. Ensure your frying oil stays between 340-360°F using a thermometer. This allows the donut to cook quickly without absorbing excess oil .

Can I bake these donuts instead of frying them?
Yes, you can bake the donuts at 375°F until golden, though they will have a different texture. This is a healthier alternative and is used in some high-protein sourdough donut hole recipes .