Fry bacon until crisp. Drain on paper towel and crumble well. Reserve 1/4 cup bacon grease.
In a medium mixing bowl, add flour, cornmeal, sugar, baking powder and salt; mix well.
To the dry ingredients in the bowl, add eggs, peanut butter, 1/4 cup bacon drippings or vegetable oil and milk; mix to incorporate. Stir in crumbled bacon.
Heat oven to 425ºF. Pour 1 Tablespoon reserved bacon drippings into a 10" cast iron skillet or 9" square baking pan. Swirl around to cover bottom and sides of skillet or pan. Place into the oven while preheating.
When oven has reached 425º, carefully remove skillet or pan. It will be VERY hot. Quickly pour in cornbread batter and return pan to oven. Bake for 20-25 minutes or until a wooden pick inserted in center comes out clean. Allow to cool in pan.
Note: If a sweeter cornbread is desired, add 1-2 additional Tablespoons of sugar, or until desired sweetness is reached.