To make the filling

1. Add together strawberry milk powder, cornstarch, and egg in a medium bowl. Whisk until light and fluffy.
2. Combine the whole milk and sugar into a small pot. Heat on medium until warmedt hrough, about 5 minutes.
3. Turn off heat and temper ~half the hot milk mixture into the egg mixture. Whisk until combined.
4. Use a fine mesh strainer to strain back into the pot with the remaining milk.
5. Return heat to medium. Whisk constantly until the mixture starts to thicken. Bring to a boil for 1-2 minutes.
6. Remove from heat, whisk in butter until smooth.
7. Transfer to a container and press plastic wrap over the surface of the filling to prevent a film from forming. Allow to cool to room temperature before refrigerating until ready to use.

To make the dough

1. Combine yeast, warm milk, and 1 tablespoon of sugar into the bowl of a stand mixer fitted with the paddle attachment. Allow to sit for 5 minutes.
2. While yeast is blooming, combine sugar, bread flour, baking powder, and salt into a large bowl. Whisk to combine.
3. Add the softened butter, egg yolks, and vanilla bean paste to the yeast mixture. Paddle together until butter is broken up.
4. Paddle in ⅓ of the dry ingredients until slightly combined, followed by another ⅓ of the dry ingredients. Once dough looks dry and shaggy, switch to the dough hook and mix on medium speed for 5 minutes until dough is smooth.
5. Transfer the dough to a floured surface and knead into a smooth ball.
6. Oil a medium bowl and place the dough into the bowl coating the top of the dough with oil. Cover with a clean kitchen towel or plastic wrap and refrigerate overnight.

To fry the donuts

1. Bring the dough to room temperature (about 2 hours).
2. Roll the dough into a 9x13 inch rectangle about ½ inch thick.
3. Cut out 3 inch rounds using a donut cutter or biscuit cutter.
4. Place donuts ~2 inches apart on a lined baking sheet. Cover loosely with plastic wrap and leave in a warm place. Allow to proof until doubled in size, about 40 minutes.
5. Fill a large pot with three inches of oil. Bring to 365°F (between 360°F-380°F range).
6. Frying four donuts at a time, fry for 2 minutes on each side.
7. Place onto a paper towel lined sheet tray.
8. While donuts are warm, toss is strawberry sugar.

To fill the donuts

1. Whip the heavy cream to medium-soft peaks.
2. Place the pastry cream into a mixing bowl fitted with the paddle attachment. Paddle on medium speed to smooth out. Transfer to a bowl.
3. Fold the cream into the pastry cream and transfer a pastry bag with a nozzle pastry tip for filling
4. Poke a hole using a skewer into the side of each donut. Fill a piping bag with cream.
5. Place nozzle into the hole and fill donuts until they have slightly expanded.
6. Serve immediately.