Step 1

In a large glass bowl, whisk together sugar and cornstarch.

Step 2

Gently mix in egg yolks, being careful not to incorporate any air. Set aside.

Step 3

Bring milk to a boil over medium heat.

Step 4

Add milk slowly to egg mixture, whisking constantly.

Step 5

Return to pot.

Step 6

Bring to a boil, stirring constantly, and continue to cook for 2 minutes.

Step 7

Turn off heat.

Step 8

Add butter and chocolate.

Step 9

Stir until melted and smooth.

Step 10

Strain through a fine mesh strainer into a clean bowl.

Step 11

Cover with plastic wrap, making sure the plastic touches the entire surface of the cream.

Step 12

Refrigerate.

Step 13

Line 2 baking sheets with parchment paper and spray with cooking spray. Set aside.

Step 14

In a medium bowl, whisk together flour and yeast. Set aside.

Step 15

In the bowl of an electric mixer, combine milk, butter, sugar, eggs, egg yolks, salt, and vanilla.

Step 16

Beat to mix.

Step 17

Add flour mixture.

Step 18

Knead until dough is smooth and elastic, about 8-10 minutes.

Step 19

Place in a covered container and proof for 30 minutes.

Step 20

Turn dough.

Step 21

Allow to proof for another 30 minutes.

Step 22

Divide dough into 2 ounce portions.

Step 23

Roll each portion of dough into a tight ball.

Step 24

Place seam side down on prepared parchment.

Step 25

Flatten slightly.

Step 26

Cover and allow to rise for 45 minutes.

Step 27

Heat oil to 325 degrees. (Let dough continue to proof while oil heats.)

Step 28

Fry doughnuts a couple at a time until golden brown and cooked through, about 3-4 minutes, flipping as necessary.

Step 29

Remove from oil and drain.

Step 30

Sift together powdered sugar and cocoa.

Step 31

Add milk.

Step 32

Stir until smooth.

Step 33

Allow doughnuts to cool.

Step 34

Fit a pastry bag with a Bismark tip or a tip large enough to inject pastry cream into doughnuts.

Step 35

Fill bag with pastry cream.

Step 36

Push tip into the center of the side of the doughnut.

Step 37

Press filling into the doughnut, pulling back as it fills.

Step 38

Dip top of doughnuts into glaze, allowing excess to drip back into bowl.

Step 39

Place on drying rack.