Grease muffins tin (cavities and the top). Set aside.
Preheat oven to 425 degrees F.
In a medium mixing bowl, whisk together the dry ingredients (flour, cocoa powder, baking powder, soda and salt). Set aside.
In a large mixing bowl of a stand mixer, mix together oil and both sugars. Mix for 2 minutes on medium speed.
Add eggs, one at a time and mix well.
Add vanilla and mix again.
With mixer on low speed, mix in dry ingredients alternating with milk.
Pour into muffin pan, filling each cavity ¾ full.
Bake 15 to 18 minutes or until toothpick inserted in the center of each muffin comes out clean.
Cool in pan for 3 minutes, then transfer onto a wire rack and cool completely before glazing.
!For the glaze:
In a medium saucepan, cook butter, milk, cocoa and corn syrup until it starts to boil. Remove from heat. Sift powdered sugar over the cocoa mixture. Whisk in until smooth. Add vanilla and whisk again.
Dip each donut muffin top down into the glaze. Set on a wire rack set over a baking sheet to catch the drips. Let sit for few minutes and then add sprinkles.