In the bowl of your stand mixer, or in a stainless-steel mixing bowl, add the yeast, 1 Tbsp of sugar and 2 Tbsp warm water. Let the yeast sit and activate for five minutes, or until bubbly.
Add the milk and vanilla to a saucepan and gently heat until steaming. Do not scald. Remove from the heat and add the butter to melt.
Add the 2 eggs and ½ cup of sugar to the activated yeast. If you're using a stand mixer, use the paddle attachment for this stage. Mix the eggs, sugar and yeast, then slowly add the hot milk, while mixing, to temper the eggs and fully incorporate.
Immediately add the flour and salt to the mixture and mix briefly using the paddle attachment. After 1 minute, remove the paddle attachment and replace it with the hook.
Knead the dough using the hook attachment for 5 to 8 minutes, until the dough comes away from the sides of the bowl and is elastic to the touch.
Cover the bowl with cling film and let rise for 1.5 hours, or until doubled.
Punch down the dough and turn it out onto a well-floured surface. Sprinkle flour over the top of the dough and, with a rolling pin, lightly roll to about 1.5-inch thickness.
Using a large, round cookie cutter, cut out the donuts. You should get 10 to 12 depending on how thinly you rolled the dough. You can re-shape the dough, allow to rise again and roll out more donuts, though I usually just cut the remaining dough, fry it and toss it in powdered sugar like a beignet.
Set the donuts on lightly floured parchment paper and let rise again for another 30 to 45 minutes (it will depend on the heat/humidity levels in your kitchen), until doubled in size.
Using scissors, cut the parchment around the donuts and fry — parchment and all — in vegetable/canola oil heated to 350˚F. The parchment will naturally lift away from the donut as it cooks; you can discard it at that point.
Fry the donuts until golden brown on both sides and cooked completely on the inside, about 90 seconds to 2 minutes per side. Drain excess oil on paper towel and allow to cool completely before filling.
Make the Crème Patissière
Whisk the egg yolks with the sugar well. Heat the milk and vanilla in a medium sized saucepan until scalded.
Mix the flour into the egg yolk mixture and add a small amount of the hot milk, to temper the eggs, then gradually pour the rest of the hot milk in (whisking constantly).
Pour the mixture back into the saucepan and return to a medium heat on the stovetop. Bring the mixture to a boil, stirring constantly so the bottom doesn't stick. The mixture will get very thick. Remove it from the heat, add the butter and whiskey and stir to combine.
Cover the crème patissière with plastic wrap, pressing the wrap over the top of the custard to avoid a skin from forming. Cool to room temperature and then refrigerate for up to three days (this can be made ahead of time).
Make the Espresso Glaze
Sift the confectioner's sugar into a large bowl. Add the vanilla, sea salt and coffee and whisk until smooth. You want the glaze to be very thick so it doesn't run down the sides of the donuts.
Finish the Donuts
Using a sharp paring knife, make a small incision into the side of each (cool) donut. Pipe the custard into the donut, then spoon on some glaze. Finished with very finely ground coffee beans.
Recipe by Food Bloggers of Canada at https://easy-fatloss.today/irish-coffee-donuts/%3C/div%3E