Prepare and Preheat
Preheat Oven: Preheat your oven to 400°F (200°C).
Prepare Pan: Lightly grease a 9x9 inch baking pan or 10-inch cast iron skillet. For a crunchy crust, melt 1 tablespoon of butter directly in the pan and swirl it to coat the bottom and sides while the oven heats up.
Combine Wet Ingredients
In the large mixing bowl, whisk together the mashed sweet potato, melted butter, milk, brown sugar, eggs, and vanilla extract until the mixture is uniform and smooth.
Combine Dry Ingredients
In the medium mixing bowl, whisk together the cornmeal, flour, baking powder, baking soda, salt, cinnamon, and nutmeg (if using). Ensure all leavening agents are evenly distributed.
Mix and Bake
Combine: Pour the dry ingredients into the wet ingredients. Use a spatula or wooden spoon to gently fold the mixture until just combined. Stop mixing as soon as the dry ingredients disappear.
Pour: Pour the batter into your prepared pan or skillet. Spread it evenly.
Bake: Bake for 20 to 25 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean.
Cool: Allow the cornbread to cool in the pan for about 10 minutes before slicing and serving.