In a large bowl, mix together flour, baking powder, cinnamon and salt; set aside. In another bowl, mix brown sugar, butter, eggs, vanilla and pecans until well blended. Add flour mixture and blend well.
Reserve 1 cup of the batter. Spread remaining batter into a lightly greased 13x9" baking pan. Bake in a preheated 350-degree oven for 15 minutes or until firm.
In a microwavable bowl, microwave caramels and milk on HIGH for 2 to 3 minutes or until caramels are completely melted, stirring after every minute. Cool for 5 minutes or until slightly thick.
Pour over baked layer in pan, spreading to within 1/2 inch of edges. Drop reserved 1 cup batter by spoonfuls over caramel layer. Cut through batter with knife several times for marble effect.
Bake an additional 15 to 20 minutes or until center is set. Cool in pan on a wire rack. Cut into bars and enjoy the caramel-y decadence.