Preheat the oven to 350 degrees. Grease a 2-quart casserole dish. In a bowl, mash the cooked carrots with butter, eggs, flour, baking powder, vanilla, extract, salt, brown sugar, cinnamon and nutmeg. Spoon into the casserole dish and top with the pecans. Bake for 45 minutes. (Serve with whipped cream, if desired.)