Spread about half of the batter in the pan. Dollop the caramel randomly over the batter, leaving a few empty spots here and there. Dollop with the remaining brownie batter, filling the empty spots and covering some of the caramel if necessary.
Use a thin spatula or knife to gently swirl and fold the batter (as you would egg whites into a batter), so that some of the caramel ends up under the brownie batter. Gently smooth the top if there are any gaps.
Bake for 30-40 minutes, rotating the pan about halfway through baking, until a tester inserted into the brownie portion comes out clean but moist. Allow to cool before cutting into squares. May be frozen.