In a double boiler or microwave, melt the chocolate with the butters and the espresso; mix well and cool.
Using an electric mixer, beat together the sugars, egg and vanilla and add the chocolate mixture; set aside. Sift the flour, cocoa powder, baking powder and salt; stir into the batter until none of the dry mixture is visible.
Transfer one-third of the batter to a greased and parchment-lined 8-by-8 inch square pan. Evenly distribute the peanut butter cups, spread another third of the batter and distribute caramels. Top with remaining batter and pecans.
Bake in a preheated 350 F oven until the brownie pulls away slightly from the sides of the pan and a tester comes out mostly clean and dry, about 40-45 minutes. Cool for at least an hour. Makes 16, 2-inch servings, each about 5 mg THC, depending on the strain.