Preheat the oven to 350 degrees F (175 degrees C). Place an 8- or 9-inch cast iron skillet into the oven to preheat.

Whisk together flour, white sugar, brown sugar, salt, cinnamon, nutmeg, and cloves in a bowl; set aside.

Beat together eggs, vanilla extract, and melted butter in a mixing bowl. Toss apples and pecans in the flour mixture, then stir into the egg mixture until combined. Melt 1 tablespoon butter in the preheated skillet, swirling to coat the pan.

Pour the batter into the hot pan, and replace into the oven. Bake until the sides are dry and a toothpick inserted into the center of the brownie comes out clean, about 40 minutes. Cool in the skillet for 20 minutes before removing and slicing.