Preheat oven to 375°F and grease a 12-inch cast-iron skillet.
In a medium bowl add 3/4 cup melted butter, 3/4 cup packed brown sugar, 1 cup flour, 1 cup rolled oats, 1 teaspoon baking soda, and the cocoa.
Mix until just combined and then press into the bottom of the prepared 12-inch cast-iron skillet.
Bake for 10 minutes.
While that is baking (and using the same bowl) put the remaining melted butter, remaining brown sugar, remaining flour, remaining oats, and remaining baking soda in the bowl and stir until combined.
When time is up, remove the skillet from the oven. Sprinkle chocolate chips over the hot bottom layer.
Pour caramel sauce over chocolate chips. (You can reduce the amount to 3/4 cup if you prefer; I like a lot of caramel.)
Press oatmeal mixture over the top of the caramel sauce. Be careful as the skillet is still very hot. (If any of the caramel is showing it may burn and turn dark brown, so I try to cover up as much as possible.)
Bake for 12-16 minutes. The edges should be darker, but not burnt. Allow the Carmelita to cool for at least 15 minutes before serving.
Store at room temperature in an airtight container.