Preheat oven to 425 degrees. Lightly spray a 6-hole donut pan with cooking spray and set aside.
In a large bowl, use a hand-held mixer to blend together the milk, sour cream and eggs.
Next, beat in the butter, vegetable oil, and vanilla extract.
Add the flour, baking powder, baking soda, and sugar. Beat into the wet ingredients.
Dump the entire batter into a large Ziploc bag. Cut one of the lower corners off the bag, and in a circular pattern, fill the donut pan about 3/4 way full. Tap the pan firmly on the kitchen counter to get the batter to settle into the pan.
Bake for 10 minutes. Remove from oven and transfer to a wire cooling rack to cool.
Repeat until all batter is used.
When the donuts have fully cooled, whisk together the confectioner's sugar, vanilla extract, milk, and food colouring until the icing is smooth and consistent. For a thicker icing, add more confectioner's sugar. For a thinner icing, add about 1/2 teaspoon of milk at a time.
Dip the donut, top side down, into the icing. Lightly shake the excess icing off the donut, or gently drag the iced part of the donut over the rim of the icing bowl.
Push the iced donut gently into a bowl of candy sprinkles to coat, or sprinkle the candy over the glazed donut.
Place the donut, iced side up, back onto the wire cooling rack and allow the icing to harden.