Preheat the oven to 375 F, and position a rack in the center of the oven. Grease a standard 12-cup muffin pan with non-stick baking spray.
In a bowl, whisk together the melted butter and sugar. Add the eggs, and whisk until smooth, then whisk in the milk and sour cream.
Separately, combine the cornmeal, flour, baking powder and salt (and the chopped pecans, if using). Add the dry ingredients to the wet, and whisk for 10-15 seconds until well combined.
Divide the batter between the cups. Bake for about 16-17 minutes, just until a toothpick comes out clean.
Remove the muffins from the pan and set on a cooling rack. Cool for 10 minutes, then serve warm. These cornbread muffins are delicious with butter and honey or pure maple syrup.
