Apple Upside-Down Cormeal Cakes

Why I Love This Recipe
Ingredients You'll Need
3/4 stick (6 tablespoons) cold unsalted butter, cut into tablespoon pieces, plus additional for greasing
3 Gala apples
1/3 cup packed light brown sugar
1 teaspoon lemon juice
1/2 cup coarsely chopped walnuts or pecans
3/4 cup all-purpose flour
1/2 cup yellow cornmeal (Do not use white cornmeal)
1/3 cup granulated sugar
2 teaspoons baking powder
1/4 teaspoon salt
1 large egg
3/4 cup whole milk (must use whole milk for recipe to work correctly)
Directions
Put oven rack in upper third of oven and preheat oven to 425 F. Butter muffin cups. Peel and core apples, then cut into 1/3-inch dice
Heat 2 tablespoons butter in 12-inch heavy skillet over moderate heat until foam subsides, then cook apples, brown sugar, and lemon juice, stirring occasionally, until liquid is reduced to a glaze and apples are tender, 5-6 mins.
Stir in walnuts or pecans and divide apple mixture among muffin