Into large bowl sift together flour, baking powder, brown sugar, salt, cinnamon, and allspice. Stir in milk, pumpkin, eggs, vanilla, and bacon drippings, and stir batter until well combined. Preheat greased griddle or skillet over moderate heat until drops of water scatter over surface. Pour batter onto griddle by ⅓ cupfuls. Cook pancakes for 2 minutes on each side, or until golden and cooked through. Serve with maple syrup, honey, or fruit.