Preheat the oven to 175°C/350°F and lightly grease the donut pans with cooking spray.

In a medium bowl, whisk the buttermilk, melted butter, eggs, and vanilla until smooth.

In a separate bowl, whisk together the flour, cocoa powder, brown sugar, salt, baking powder, and espresso powder.

Mix the dry ingredients into the wet ingredients in three additions, gently folding with a spatula.

Add the gel food coloring as needed with a toothpick until the desired color is reached.

Pour the batter into a piping bag and divide it between 12 holes in the donut pans.

Bake for ten minutes, then transfer the trays to a wire rack to cool.

While the donuts cool, make the glaze by beating the cream cheese until smooth with a stand mixer or handheld whisk.

Add the vanilla extract and mix again.

Gradually add the powdered sugar and mix by hand until mostly incorporated.

Beat with a mixer until smooth, adding milk as needed. Coloring is optional.

Dip the cooled donuts into the glaze and serve.