Fill each jar about half full with batter (it will rise). Gently spoon equal amounts of mango puree on top. Cover jars with a round of wax paper and a round of foil. Secure with kitchen twine, cotton string or a screw ring (if your canning jars have this type of two-part lid). Add an inch or two of water, a trivet and jars to a pressure cooker or large cooking pot. Steam in pressure cooker at 15 psi for 14 minutes, natural release, on a stovetop, cook covered, at a steady simmer for 20 minutes. Remove from heat. Let rest for 5–10 minutes. Carefully remove jars from pot, remove covers and serve while warm. Eat right from the jars. (This is a “make now, eat now” dessert!) Makes 4–5 servings.