Mix the Dough (Day 1)
Add the all-purpose flour, bread flour, pastry/cake flour, pumpkin purée, sugar, optional sourdough starter, yeast, milk, eggs, and salt to your mixer bowl. Hold back the butter.
Mix on low speed until all dry patches disappear and the dough begins developing cohesive gluten structure.
With the mixer running, add the softened butter gradually in several additions. Continue kneading until the dough is smooth, elastic, and glossy.
Verify gluten development with the windowpane test (dough should stretch into a thin, translucent membrane without tearing).
Ferment & Chill Overnight
Shape into a ball, place in a greased container, cover, and let sit at room temperature for 30–40 minutes to start yeast activity.
Transfer to the refrigerator and chill overnight to firm up the butter and build flavor.
Shape the Donuts (Day 2)
Remove cold dough from the fridge and divide into 70 g portions.
Bismarck Rounds: Shape each portion into a tight, smooth ball and place seam-side down on an individual parchment square.
Pumpkin Shapes (Optional): Tie 4 crisscrossed strands of kitchen twine loosely around each dough ball so it can expand between the strings into 8 sections.
Final Proof
Cover shaped donuts and proof at room temperature for 1½–2 hours until visibly larger, soft, light, and airy to the touch.
Fry at 320°F (160°C)
Heat avocado oil in a deep pot to 320°F (160°C).
Gently lower proofed donuts into the oil (using the parchment square to prevent deflating).
Fry for 1–2 minutes per side until golden brown and cooked through.
Drain on a wire rack or paper towels. Snip and remove twine if using, then glaze, roll in sugar, or fill with cream while warm!