Preheat the oven to 350 degrees.
In a large bowl, mix 2 cups of flour, 1 and 1/2 cups of sugar, the baking powder, 1 teaspoon of cinnamon, 1/2 teaspoon of nutmeg and1/2 teaspoon of salt
In a separate bowl, mix the egg, milk, 2 tablespoons of melted butter and vanilla
Mix the wet ingredients in with the dry until just combined
Prepare your doughnut pan with non stick spray
Fill each cavity about 3/4 full
Bake for 15-18 minutes
Once the doughnuts are springy to the touch, transfer them onto a cooling rack
For the topping, melt the remaining 4 tablespoons of butter in a medium sized bowl
In a separate bowl, combine 1/2 cup of sugar and 1/2 teaspoon of cinnamon
Dip each cooled doughnut into the butter and then into the cinnamon sugar on both sides