Preheat oven to 350 degrees.
In a large bowl, buttermilk, sour cream, melted butter, vegetable oil, brown sugar, and sugar. Whisk together until ingredients are combined. Add instant vanilla pudding mix and vanilla extract and continue to whisk together. Add one egg at a time and continue whisking.
In a separate bowl, combine flour, cornmeal, baking powder, baking soda, and salt. Mix together. Add to wet ingredients.
Spray a cast iron skillet or 9 inch round baking pan with oil. Add batter and bake 35-40 minutes, until a tooth pick comes out clean.
Allow cornbread to cool for 5-10 minutes.