Preheat oven to 400 degrees.
Use an 8" skillet (thick cornbread) or a 9" (thin cornbread). Spread cracklings in a medium-sized skillet.
Add 3 tablespoons of vegetable oil. Stir until evenly coated.
Warm on top of stove over low-medium heat. Stir constantly for 2-3 minutes until vegetable oil and cracklings are golden brown. Do not leave stove while cooking.
Turn off heat. Sprinkle salt over cracklings. Stir well. Crush to small pieces using heavy spatula or spoon. Set aside.
In medium-sized bowl, combine corn muffin mix, self-rising white corn meal mix, sugar (if using), egg, and buttermilk. Stir together until smooth. Small lumps okay.
Use a large spoon to scoop cracklings and some of drippings from skillet. Use leftover drippings to grease muffin tin.
Stir together cornbread batter and 3/4 cup of cracklings until evenly combined. Set batter and leftover cracklings aside.
Place 1/2 teaspoon of drippings in each muffin's cup (6 cups total). If you don't have enough drippings, use 1/2 teaspoon of vegetable oil.
Pour 2-1/2 tablespoons of cornbread batter into each cup.
Reduce oven to 375 degrees. Bake 10 minutes. Carefully remove from oven. Place 1/2 teaspoon of cooked/crumbled cracklings on top of each muffin.
Return to oven. Bake 10 to 15 minutes OR until golden brown and knife inserted in center comes out clean.