Preheat the oven to 350℉. Spray the cups of a 12-cavity muffin pan with nonstick spray.
In a medium bowl, whisk together the flour, baking powder, salt, baking soda and nutmeg.
In another medium bowl, use an electric mixer to combine the sugar and butter on medium speed until the color lightens. Mix in the eggs and vanilla extract.
In a small bowl, whisk together the milk and the buttermilk.
Alternate adding the dry ingredients and the milk mixture to the creamed butter, one-third at a time, mixing well after each addition (on low speed). Start with one-third dry, mix well, then add one-third of the milk mixture, and repeat two more times with the remaining ingredients.
Spoon equal amounts of muffin batter into the prepared muffin pan. Bake for 18 to 20 minutes or until golden brown and the center of each muffin springs back when touched. Let cool completely in the pan.