In a medium bowl, combine the flour, baking powder, cinnamon, nutmeg, allspice, and sugar
In a large bowl, whisk the pumpkin with the eggs, milk, oil, and vanilla. Add the dry ingredients and stir until well blended. Fold in chopped pecans, if using.
Brush a griddle or skillet with oil and place it over medium heat.
Pour about 1/4 cup of the batter onto the hot oiled griddle and cook until bubbles form and the edges look dry. Turn and brown the other side.
Serve pumpkin pancakes with butter and warmed pure maple syrup. If desired, top with toasted pecan halves.