Preheat the oven to 350 F and grease one 9" Loaf Pan. Start by mixing together the Butter, brown sugar, pumpkin, and eggs in a medium bowl. Next, mix the cinnamon, baking powder, baking soda, and flour together in a separate bowl. Pour the dry ingredients into the pumpkin mixture and mix well. Spread the mixture into the loaf pan and bake for 55 minutes or until a knife comes out clean when inserted into the middle of the bread.