• In a small bowl, dissolve yeast in warm water for about 5 minutes, until frothy.
• In the bowl of a mixer or in a large bowl with a hand mixer, whisk together flour, espresso powder, sugar, and salt.
• Add in milk, butter, egg yolks, and yeast mixture and blend together using the mixer’s dough hook (if you don’t have a mixer with dough hook, a hand mixer is fine). Form dough and then increase mixer speed to medium and let mix for about 3 minutes.
• Sprinkle the dough with some flour, cover with a kitchen towel, and place in a warm place for about two hours, so it can rise.
• Place dough on a lightly floured surface and roll out so it’s about ½ inch thick. Using a biscuit cutter or the top of a drinking glass (or other round object), cut out as many rounds from the dough as you can. I used a 3-inch cutter and got 12. Place rounds on a lightly floured baking sheet. Cover the baking sheet with your kitchen towel and let rise again for about 30 minutes.
• Heat 2.5 inches of canola oil in a large pot until it reaches 350 degrees. Add a few dough rounds to the oil and fry for about a minute on each side until they start turning golden. Place fried doughnuts on a paper towel-covered plate to rest. When finished frying, move doughnuts to a wire rack to cool completely.
• Fill a pastry bag with long tip with custard. Pierce each doughnut and squeeze some custard into the middle. Drizzle a layer of icing over the top.

Vanilla Latte Custard

• Bring milk and vanilla to a simmer in a large saucepan and then remove from heat.
• In a separate large bowl, beat sugar and egg yolks together until thick. Stir in cornstarch.
• Slowly whisk half of hot milk from the saucepan into the bowl with the egg mixture to temper the eggs. Then add that egg/milk mixture back into the saucepan and whisk over medium heat until the mixture is thickened and coats the back of a wooden spoon. This will take about 4 minutes.
• Remove the custard from the heat and stir in espresso water mixture.
• Pour custard into a separate bowl and cover with plastic wrap. Make sure the plastic wrap is actually touching the custard so that a skin doesn’t form. Put the custard in the fridge to cool completely.

Vanilla Icing

• Whisk together confectioners' sugar, 3 tablespoon whole milk, and vanilla. If icing is too thick, add remaining ½ tablespoon milk a little bit at a time until desired consistency is reached.