Dangerous Donuts

If you are filling the donuts with the vanilla custard, you should make it first so it can set a minimum of four hours in the refrigerator. In contrast, the chocolate glaze is best made immediately before dipping. If the glaze does cool and harden, you can re-liquify it with about 10 seconds in the microwave.

Vanilla Custard

In a small saucepan not yet on the stove, whisk together the sugar, cornstarch, and salt.

Add some of the milk (about 1/4 cup) and the yolks, and whisk until the texture is even. Now add the rest of the milk as well as the heavy cream and whisk until thoroughly combined.

Place the pan on the stove on low-med heat and whisk without pausing until the mixture thickens. Note that the thickening will happen somewhat suddenly, so stay attentive to prevent lumps. Switch to a spatula and stir until it doesn't flow off the spatula. A thicker custard helps the filling stay inside the donut.

Turn off the heat, add the butter and vanilla extract and mix until they're incorporated.

Let the custard cool about 20 minutes, mixing occasionally to prevent a skin from forming. Transfer to a bowl and cover with plastic wrap right up against the custard. Refrigerate for at least 4 hours.

Dough

In the bowl of a stand mixer with the paddle attachment, whisk together the two flours, cocoa powder, sugar, and salt. Mixing by hand is fine also. You will need to do the last step of adding the butter via hand-kneading.

In a smaller bowl, combine the milk and coffee. Add the yeast and let it bloom for a couple of minutes.

Pour the milk-coffee-yeast mixture into the dry ingredients, add the egg, the yolk, and the vanilla extract. Mix on low speed for about 30 seconds and then on medium speed for about 2 minutes.

Add the butter pats and mix on medium-high speed for 1-2 minutes.

When the butter is fully incorporated into the dough, scrape it out of the bowl and off the paddle. Transfer the dough to a lightly oiled bowl or straightwalled container. Mark the level of the dough and cover it.

Let the dough rest 5-10 minutes, then coil-roll it until it is taut and smooth. Here is a video of how to do this.

Return the dough to the container, cover, and let it rise until it has doubled in size. This will take 1-2 hours depending on your dough and ambient temperature. Made with room temperature coffee and cold milk, my dough took 1 1/2 hours to double.

Place the dough on a lightly floured work surface and divide it into 6 pieces, 75-80 grams each.

Roll the pieces into balls and place them on a baking sheet lined with parchment paper. Cover with a barely-damp tea towel and let rise again until almost doubled in size. This should take 1-2 hours depending on your dough and ambient temperature. My dough proofed for about 1 hour in a 75°F kitchen.

Preheat the oven to 325°F and bake the donuts for 13-15 minutes or until the internal temperature is over 190°F. If you choose to make larger donuts, add about 1 minute per 10 grams additional dough in each ball e.g. 95-100 gram dough balls need 15-17 minutes bake time.

Remove from the oven and let cool on a rack. Keep the parchment covered baking sheet handy as you'll use it to catch drippings when you fill and glaze the donuts, though the custard and chocolate glaze should be thick enough that almost nothing drips.

Donut Assembly Part 1 (Filling)

When the donuts are cool, place the cooling rack on your parchment-lined baking sheet.

Use a chopstick to poke a hole in the side of each donut going about 2/3 of the way into the donut. You can also use a paring knife, poking twice in the same spot to make an X.

Put a Bismark piping tip into a pastry bag. Fold the edges of the bag outward and place in a tall glass to stabilize. Spoon the filling into the bag. Using a Ziploc bag or pastry bag without a tip is an option too but more difficult. Make the cut in the corner of the bag small, around 1/8 inch. It will likely stretch and you can always make it bigger if needed.

Insert the pastry tip into each donut and fill it.

Chocolate Glaze

Combine the chocolate and heavy cream in a microwave safe bowl. Microwave 20 seconds, remove, and stir with a spoon. Microwave another 20 seconds, remove, and stir with a spoon for a while. As you stir and distribute the heat, the almost-melted pieces will fully melt and the color will shift from pale to dark. If this doesn't happen after a minute or so, microwave the bowl another 10 seconds.

Donut Assembly Part 2 (Glazing)

After the donuts are all filled, dip them into the chocolate glaze, rotating and re-dipping as needed to coat the top. Set on the cooling rack. Sprinkle with caraway seeds if desired. The glaze will take several hours to dry though you can certainly eat the donuts while the chocolate is messy. I did.

Store in a covered container. Custard does not freeze well, so it's best to eat these in about three days.