• Preheat oven to 325 degrees and lightly spray a doughnut pan with cooking oil.
• In a large bowl, whisk together flour, sugar, baking powder, and salt.
• In a separate smaller bowl, whisk together eggs, melted butter, Guinness, and chocolate milk.
• Stir the wet ingredients into the dry ingredients until just combined, taking care not to over-mix. 
• Fill each cavity in the doughnut pan about ¾ of the way with batter. I like to put batter in a plastic bag, cut off the corner, and squeeze the batter into the doughnut pan (you could also use a pastry bag).
• Bake doughnuts for 8-10 minutes until they're cooked through and light and springy to the touch. Let cool in the pan for a few minutes before removing to a cooling rack to cool completely. Repeat with second batch of doughnuts (if your doughnut pan only holds six). 
• Once doughnuts are completely cooled, frost with Irish whiskey frosting and add sprinkles, if desired.

Irish Whiskey Frosting

• In a large bowl, whisk together confectioners' sugar, softened butter, salt, and 4 Tbsp whiskey until well combined. If frosting is still too thick, add additional Tbsp of whiskey.
• Add green food coloring 1 drop at a time and stir until it's blended and desired color is achieved.