Preheat oven to 350°F. Using cooking spray, grease donut pans and set aside.
In a large bowl, sift together GF flour, cocoa, baking soda, and salt. Next add the sugar and whisk together.
In a large measuring cup, mix together the oil, milk, vinegar, and vanilla. Whisk to combine.
Create a well in the center of the dry ingredients, add wet and whisk until just combined, trying not to overmix the batter. Next fold in the food colouring. I used 1/2 tbsp of powder but you could use gel or liquid.
Pour the batter into a large piping bag. Snip off the top and pipe the batter into the prepared donut pan filling about 1half way. (if you are using regualr sized donut pans you will get about 12 donuts, if you are using smaller ones you may get about 15-18 donuts depending on the pan size)
Bake in the center of the oven for about 10 - 12 minutes until the donuts are cooked through and spring back when you touch them. Remove from oven, let stand for a couple of minutes then remove from pan and let cool completely on a wire rack.
To prepare the glaze for the donuts, combine the cream cheese, vanilla and 1 teaspoon of milk in a bowl, whisk to combine. Add 1/2 cup powdered sugar and milk again until combined and a glaze like consistency forms. If you need to loosen up the mixture add more milk or if it needs to thicken add more powdered sugar.
Once donuts are cool, drzzle them wiht the glaze or dip them to cover the top and finish wiht sprinkles.