Preheat your oven to 375°F (190°C) and grease a muffin tin or line it with muffin cups.
In a large bowl, sift together the flour, sugar, baking powder, salt, cinnamon, and nutmeg.
In another bowl, mix together the milk, vegetable oil, beaten egg, and vanilla extract.
Add the wet ingredients to the dry ingredients and stir just until combined. Do not overmix.
If using, fold in the chopped pecans or walnuts.
Fill the muffin cups about 2/3 full with the batter.
Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for a few minutes before transferring them to a wire rack to cool completely.