Preheat the oven to 350°F/176°C and spray your donut pan with baking spray. This recipe makes 12-15 donuts so have a more pans handy.
Add the cooled melted butter, oil, eggs, vanilla extract, and buttermilk to a mixing bowl and whisk until well combined.
In a large mixing bowl, mix together the flour, granulated sugar, baking powder, baking soda, nutmeg, and salt until well combined.
Add the wet ingredients to the dry and mix until smooth and combined being careful not to over mix the batter. The mixture will be quite thick, but all of the flour should mix into the dough. If it seems stiff or dry, add a little more buttermilk.
Pipe the dough evenly into the pans, filling the cavities ¾ full.
Bake 12 to 14 minutes or until a cake tester comes out clean.
Remove from the oven and let cool in the pan for 10 minutes. Then transfer to a cooling rack to cool for a further 15-20 minutes.
For the Glaze
Combine all the ingredients in a medium bowl and mix until smooth.
To Glaze the Donuts
Place baking paper under wire racks (this is to catch the excess glaze). Coat the donuts with the glaze by dunking them into the glaze. Place the glazed donuts on the wire rack to set. After about 20 minutes, the glaze will set and harden.
Properly measure flour by spooning the flour into the measuring cup and then leveling off the top or for most consistent results use a kitchen scale.
Be careful not to over mix the batter when blending the wet and dry ingredients. Over mixing can cause the donuts to be dense and not light and fluffy.
Use room temperature ingredients as they blend together better when they’re all at the same temperature.
To easily fill the pan, pipe the dough into the cavities using a piping bag, or to use a large ziplock bag, just cut a corner off the bottom of the bag and pipe the batter into each cavity.
Glazed donuts are best when eaten the day they are baked.