Preheat the oven to 425F. Grease a donut pan.

In a bowl, mix together the melted butter, vegetable oil and sugar. Mix in the eggs and vanilla. In another bowl, combine the baking powder, salt, baking soda and flour. Mix the dry ingredients into the sugar mixture alternately with the buttermilk. Mix just until combined.

Transfer one-third of the mixture into a pastry bag or ziptop bag. Divide the remaining batter into 2 bowls. Tint one bowl with red food coloring and the other with blue food coloring. Lightly mix to distribute the color. Transfer each of the colored batters into separate pastry bags.

Pipe an equal amount of each colored batter into the donut pan. If desired, drag a toothpick through each of the colors to create a tie-dyed effect.

Bake the donuts until the centers spring back when lightly touched, 8-10 minutes. Allow the donuts to cool completely.

To make the glaze - combine the powdered sugar and vanilla. Add in the cream, one tablespoon at a time, until you reach the desired consistency.

Dip the cooled donuts into the glaze. If the glaze starts to harden before you are finished dipping the donuts, mix in more cream. Allow to set up for a few minutes before serving.