Preheat oven to 425 degrees F. Grease a 13x18 inch baker's half sheet pan.

Dry Ingredients: In a large bowl, combine the flour, brown sugar, baking powder, baking soda, allspice, cinnamon, and salt.

Wet Ingredients: In a separate bowl, combine the buttermilk, pumpkin, eggs, and melted butter.

Combine: Add the wet ingredients to the dry ingredients and stir until just incorporated. Don't overmix. Stir in 4 to 6 tablespoons of milk, a little at a time, until the batter is thick but pourable.

Bake: Pour the batter into the prepared pan and spread evenly. Add toppings, if desired. Bake 10 to 12 minutes, until the center springs back.

Serve: Cut into squares and serve warm with homemade syrup.