Preheat the oven to 425˚F (218˚C). Lightly grease a mini donut pan. If you have 2 pans, grease both pans.
In a large mixing bowl with an electric mixer fitted with a paddle attachment, beat the butter, vegetable oil and sugars until smooth. Add eggs and beat to combine.
With a spatula, stir in the baking powder, baking soda, salt and vanilla. Mix well.
Stir and add the flour and milk to the butter mixture alternately in 3 additions, by starting and finishing with the flour. Mix until just combined. Do not overmix. Stir in the chocolate chips.
Spoon the batter into a piping bag or Ziploc bag, fill the donut pan with batter all the way up to the rim.
Bake in the oven for about 6 – 8 minutes. Test the donuts with a toothpick for doneness. The toothpick should come out clean. Remove from oven and cool in the pan for 5 minutes. Transfer the donuts to a cooling rack and cool completely. If you have more batter, clean and dry the donut pan. Lightly grease the pan, fill and bake again.
For the glaze, in a medium bowl, stir together the hot water and coffee powder until dissolved. Add powdered sugar, corn syrup, vanilla and salt. Whisk until smooth. Let it sit for 5 minutes. Whisk again. Glaze the donuts and let them set at room temperature for 20 minutes.
