Preheat oven to 350°F. Spray a donut pan with oil.
In a large bowl whisk together the butter, oil, sugar, eggs, vanilla, milk, pumpkin puree, and sour cream.
Add the flour, baking powder, baking soda, pumpkin pie spice, nutmeg, and salt. Stir to combine.
Divide the mixture between your donut pans.
Bake for 13 to 16 minutes for standard donuts, 11 to 13 for small donuts, or 7 to 8 minutes for mini donuts, or until a toothpick comes out clean.
Allow to cool in the pans for 10 minutes and then carefully remove to a cooling rack. Allow to cool for 20 minutes.
To glaze, whisk together the powder sugar and salt. In a small dish, stir together the maple syrup, vanilla, and whole milk.
Dip the donuts in the glaze and serve immediately.
Makes 14 small.