High Protein Sourdough Discard Donuts with Vanilla Cream

Description These golden, baked sourdough discard donuts deliver an airy crumb with a subtle tang, perfectly balanced by a rich, velvety vanilla custard center. By pairing the depth of fermented discard with ultra-fine almond flour and whey protein, this bakery-style treat satisfies cravings while keeping sugars low. It is an indulgent, high-protein dessert that easily fits mindful low-carb eating without sacrificing authentic bakery texture.

Can These Sourdough Discard Vanilla Custard Donuts Support Weight Loss Goals? Yes. Unlike traditional deep-fried pastries loaded with refined sugars, these baked donuts utilize high-satiety ingredients. The combination of whey protein isolate, whole eggs, and almond flour elevates protein and healthy fat levels, which delays gastric emptying and curbs mid-day sugar cravings. Using a low-glycemic, keto-friendly sweetener prevents the insulin spikes often linked to fat storage, making it a filling treat that fits easily into a calorie-controlled regimen.

Does This Recipe Fit a High Protein Lifestyle? This recipe is engineered specifically for active, protein-conscious lifestyles, providing over 14 grams of protein per pastry. Swapping standard pastry flour for a blend of almond flour and whey isolate keeps net carbohydrates to just 6 grams per serving. The sourdough discard provides prebiotics and elasticity without dominating the carb profile, while the protein-reinforced custard delivers essential amino acids. It easily functions as a post-workout treat or a macro-friendly breakfast option.

My Personal Experience

Chilling the protein custard for at least two hours is crucial; it allows the whey to hydrate fully and prevents runny filling when piping into warm donuts.
Using 100% active-dry sourdough discard straight from the fridge gives the baked dough an ultra-tender brioche texture without requiring yeast proofing.
Brushing the warm donuts with melted ghee instead of vegetable oil yields a rich, authentic bakery aroma that masks any chalkiness from the protein powder.

Perfect For

Post-workout fuel and high-protein breakfast spreads
Macro-friendly afternoon treats for low-carb lifestyles
High-protein desserts for guilt-free weekend baking
Clean meal-prep snacking that staves off sugar crashes

Why You’ll Love This Recipe

Bakery-Level Fluffy Crumb: The fermentation of the sourdough discard naturally tenderizes the almond flour base, yielding a pillowy, non-rubbery crumb.
Silky Macro-Friendly Core: The custard replaces heavy cornstarch with egg yolks and vanilla whey, producing a luscious cream with zero chalky aftertaste.
Low-Mess Oven Baked: Baking in a donut pan eliminates hot frying oil, cutting excess saturated fats while ensuring uniform, golden browning.

Common Mistakes to Avoid

Overfilling the Donuts: Pushing the piping nozzle too deep splits the delicate low-carb pastry seams; stop piping as soon as the top visibly swells.
Baking at Excessively High Heat: Whey protein burns quickly; keep the oven strictly at 175°C (350°F) to prevent a dry, bitter outer crust.
Piping Warm Custard: Filling the donuts before the custard sets results in a dissolved, soggy interior rather than a defined creamy pocket.
Over-mixing the Batter: Aggressively beating the wet and dry ingredients over-activates the sourdough gluten, resulting in a dense, rubbery ring.

Required Equipment

Silicone or Non-Stick Donut Pan: Prevents fragile low-carb dough from sticking and guarantees clean releases without excess greasing.
Bismarck Piping Tip (Long Filler Tip): Injects custard directly into the center of the baked donut without rupturing the outer crust.
Whisk and Heavy-Bottomed Saucepan: Ensures gentle, even heat distribution so the egg custard thickens smoothly without curdling.

Storage Instructions Store filled donuts in an airtight, parchment-lined container in the refrigerator for up to 4 days; chilled storage keeps the custard stable and bacteria-free. To freeze, wrap unfilled baked donuts tightly in plastic wrap for up to 2 months, thawing at room temperature before injecting freshly made custard.

Recipe Details

Preparation Time: 20 minutes
Cooking Time: 18 minutes
Total Time: 38 minutes (plus chilling time)
Servings: 6 donuts
Best Season: All-season
Total Calories: ~210 kcal per donut (approximate estimate)

Golden, tender baked sourdough rings are injected with a velvety vanilla custard, offering authentic bakery luxury packed with clean protein and minimal net carbs.

Ingredients

Donut Dough:

100g (1/2 cup) sourdough discard (unfed, 100% hydration)
80g (3/4 cup) superfine blanched almond flour
30g (1 scoop) unflavored or vanilla whey protein isolate
45g (3 tbsp) granulated erythritol or monk fruit blend
1 tsp baking powder
1/4 tsp fine sea salt
2 large whole eggs (room temperature)
45ml (3 tbsp) unsweetened almond milk
1 tsp pure vanilla extract
15g (1 tbsp) melted butter or coconut oil (for brushing)

High-Protein Vanilla Custard Filling:

180ml (3/4 cup) unsweetened almond milk
2 large egg yolks
25g (2 tbsp) powdered erythritol
25g (1 scoop) vanilla whey protein isolate (Note: do not boil after adding)
1 tsp pure vanilla bean paste or extract
1/4 tsp xanthan gum (for thickening)

Directions

Make the Custard: Whisk egg yolks, powdered erythritol, and unsweetened almond milk in a small saucepan over medium-low heat. Stir constantly for 4–5 minutes until the mixture lightly coats the back of a spoon (do not boil).
Thicken and Chill: Remove saucepan from the heat; whisk in vanilla bean paste, xanthan gum, and vanilla whey isolate until smooth and glossy. Cover surface directly with plastic wrap and refrigerate for at least 1.5 hours until set.
Prep the Oven: Preheat oven to 175°C (350°F) and lightly spray a 6-cavity donut pan with avocado oil.
Mix Batter: In a bowl, whisk almond flour, whey protein isolate, granulated sweetener, baking powder, and salt. In a separate bowl, whisk sourdough discard, eggs, almond milk, and vanilla extract until uniform. Fold wet into dry until just combined into a thick batter.
Bake: Pipe or spoon the batter evenly into the donut wells. Bake at 175°C (350°F) for 12–14 minutes until tops spring back to the touch and edges are light golden brown.
Cool and Fill: Transfer donuts to a wire rack to cool completely. Fit a piping bag with a long filler nozzle, load the chilled custard, puncture the side of each donut, and gently squeeze until filled.

Nutrition Facts (Per Serving – Approximate)

Calories: 210 kcal
Fats: 11g
Cholesterol: 125mg
Sodium: 140mg
Potassium: 165mg
Total Carbohydrates: 8.5g
Fiber: 2.5g
Net Carbs: 6g
Sugars: 1.5g
Protein: 14g
Calcium: 85mg

Notes

Storage & Reheating: Store filled donuts strictly in the fridge; if desired, let sit on the counter for 10 minutes before eating rather than microwaving, which melts the custard.
Allergy Swap: Replace almond flour with sunflower seed flour (1:1 ratio) for a nut-free version; note the color may turn slightly green due to chlorophyll reacting with baking powder.
Flavor Boost: Add 1/4 teaspoon freshly grated nutmeg to the donut batter and use real vanilla bean paste in the cream for authentic French bakery flavor.

Frequently Asked Questions

Can I use active sourdough starter instead of discard? Yes, fed starter works well, though it yields a slightly lighter and tangier donut.
Why did my custard turn lumpy? The heat was likely too high while cooking the yolks, causing the eggs to scramble before the protein was incorporated.
Can I fry these donuts instead of baking them? This almond flour and discard batter is formulated for baking; deep-frying will cause the fragile rings to break apart in hot oil.
Can I use plant-based protein powder? Yes, though pea and soy proteins absorb more moisture, so add an extra 1–2 tablespoons of almond milk to balance the texture.