1. Prepare the Dough:
- In a large mixing bowl, combine the warm milk, yeast, and sugar. Let it sit for 5 minutes until frothy.
- Add the eggs, salt, and half of the flour. Mix until well combined. Gradually add the remaining flour and softened butter, mixing until a soft dough forms.
- Turn the dough out onto a floured surface and knead until smooth and elastic, about 10 minutes.
- Place the dough in a greased bowl, cover, and let it rise in a warm place until doubled in size, about 1 to 1.5 hours.
2. Make the Vanilla Custard:
- In a saucepan, heat the milk and vanilla extract until hot but not boiling.
- In a bowl, whisk together the egg yolks, sugar, and cornstarch. Gradually whisk in the hot milk.
- Return the mixture to the saucepan and cook over medium heat, stirring constantly until the custard thickens.
- Transfer to a bowl, cover with plastic wrap touching the surface to prevent a skin from forming, and chill in the refrigerator.
3. Make the Chocolate Custard:
- Follow the same steps as the vanilla custard, adding the cocoa powder to the egg yolks, sugar, and cornstarch mixture before whisking in the hot milk.
- Cook until thickened, then chill in the refrigerator as well.
4. Fry the Donuts:
- Once the dough has doubled in size, turn it out onto a floured surface and roll it out to about 1/2 inch thickness.
- Use a donut cutter or a large round cutter to cut out donut shapes.
- Let the cut donuts rise for about 30 minutes.
- Heat the oil in a deep fryer or large pot to 350°F (175°C).
- Fry the donuts in batches until golden brown, about 1 minute per side. Transfer to a paper towel-lined plate to drain.
5. Fill the Donuts:
- Once the donuts are cool, use a piping bag fitted with a narrow tip to fill half of the donuts with vanilla custard and the other half with chocolate custard. Insert the tip into the side of each donut to fill.
6. Serve:
- Dust the filled donuts with powdered sugar before serving.
Enjoy your Custard Cream Donuts as a decadent breakfast treat, a satisfying snack, or a delightful dessert. The combination of soft, airy dough with the creamy richness of vanilla and chocolate custard makes these donuts a crowd-pleaser that’s sure to impress.