To make the caramel, combine all ingredients in a saucepan over medium-low heat. Bring to a low boil and then reduce to a simmer, stirring frequently, until thickened (about 5 minutes). Remove from heat.
Stir the dry ingredients into the bowl with the sweet potato mixture. Stir well, and then pour batter into the prepared baking dish. Spread evenly - the batter will be thick.
Bake at 350 F for 35 minutes, until cooked throughout. The blondies will be fudgy, but a knife should come out clean.