Whisk the dry ingredients. In a large bowl, combine flour, sugar, baking powder, baking soda, salt, cinnamon, ginger, and nutmeg. Stir to evenly distribute the leaveners and spices.

Mix the wet ingredients. In a separate bowl, whisk pumpkin puree, sourdough starter, egg, oil or melted butter, milk, and vanilla until smooth.

Combine and rest. Pour the wet mixture into the dry ingredients. Stir gently until just combined. If the batter looks very thick, add a splash of milk. Let the batter rest for 10 minutes to hydrate the flour and relax the gluten.

Preheat the griddle. Heat a nonstick skillet or griddle over medium heat. Lightly grease with butter or oil. You want the surface hot but not smoking.

Cook the pancakes. Scoop 1/4 cup batter per pancake onto the hot surface. If using mix-ins, sprinkle them on top right after pouring. Cook until the edges look set and small bubbles appear on the surface, about 2–3 minutes.

Flip and finish. Flip gently and cook another 1–2 minutes, until the centers are cooked through and the bottoms are golden.

Serve warm. Stack pancakes on a plate, and serve with butter, maple syrup, or a dollop of yogurt. A dusting of cinnamon sugar or a drizzle of warmed apple butter is also great.