I decided to bake a cake tonight (just because -- mostly an excuse to play with fondant) and am bored with my normal layer fillings. I have some leftover ganache with hazelnuts, some delicious jam, and plain frosting. What's intriguing me, though, is a small container of dulce de leche I found in my fridge. (It's not old, it just slipped my mind.) Problem is, there's not a whole lot and it's VERY thick. I have about 6 or 7 oz. left from an 8.82-oz container. Is there anything I can thin it out with to spread on the inside, or should I just use something else? The cake is two 9-inch rounds.