To make the donuts, preheat the oven to 350°F. Grease a donut pan with cooking spray or softened butter.

Whisk the flour, cocoa powder, baking powder, soda and salt in a medium-sized bowl.

Place the oil, the sugars, and vanilla in a large bowl and whisk to combine. Add the egg and yolks, one at a time, and continue whisking until smooth.

With a flexible spatula, gently fold the dry ingredients into the wet ingredients in three additions and

the buttermilk in two, beginning and ending with the dry.

Fill each donut mold about 3/4 of the way full with batter.

Bake for 8-10 minutes, rotating at the halfway point, until a toothpick comes out with a moist crumb or two and the donut springs back when you press it. Let cool slightly and then remove from the pan to cool completely.

To make the glaze, combine all of the glaze ingredients in a small, shallow bowl and whisk until smooth and fully incorporated, adding more buttermilk if necessary, or sugar, until pourable and thick, and adjusting the food coloring until the purple color is to your liking.

To glaze the donuts, dip one side of each donut into the glaze and then lift it out, allowing the excess glaze to drip back into the bowl. Place the glazed donuts, glaze side up on a drying rack set inside a cookie sheet until set.

The glazed donuts are best enjoyed the day they are made.