Preheat your oven to 350 degrees
In a large bowl, whisk together 1 large egg plus 1 egg yolk, 2/3 cup of sour cream, 2 teaspoons of vanilla extract, 1/4 cup of whole milk, 4 tablespoons of melted butter and 2/3 cup of brown sugar
Place a mesh sifter over the bowl and add 1/2 teaspoon of salt, 1 teaspoon of espresso powder, 1/3 cup of cocoa powder, 1 teaspoon of baking powder, 1/4 teaspoon of baking soda and 1 1/2 cups of all purpose flour into the sifter
Sift the dry ingredients into the wet ingredients
Mix the ingredients until just combined
Grease your doughnut pan
Fill each cavity 2/3 of the way
Bake the doughnuts for 8-12 minutes (depending on the size of your doughnuts) or until they feel springy and set to a light touch
Transfer the baked doughnuts onto a cooling rackĀ
While the doughnuts are cooling, make the dark chocolate glaze by whisking 1 tablespoon of special dark cocoa powder, 1 tablespoon of unsweetened cocoa powder, 2 tablespoons of canola oil, 1 teaspoon of vanilla extract, 1 cup of confectioners sugar and 2 tablespoons of hot water in a small bowl until smooth and glossy
Once the doughnuts have come to room temperature, dip them into the chocolate glaze (top side down) and then return them to the cooling rack
Sprinkle the tops with crushed pretzels while the chocolate glaze is still soft
Allow the garnished doughnuts to sit on the cooling rack for about 15 minutes so the chocolate glaze can set up
Store in an airtight container at room temperature