Preheat oven to 350 degrees F.
Spray 24 regular sized muffin tins with nonstick cooking spray and set aside.
In a large mixing bowl, add the melted butter, pumpkin puree, eggs, sugar, and vanilla. Whisk until smooth.
In another mixing bowl, combine the all-purpose einkorn flour, baking soda, baking powder, cinnamon, nutmeg, ginger powder, and salt. Mix until combined.
Gently fold the pumpkin puree mixture in with the dry ingredients. Mix until combined then cover with plastic wrap and let the batter sit for at least 20 minutes (or overnight in the fridge) to give time for the Einkorn flour to absorb the liquid.
Once the batter has rested, stir once more to make sure there aren't any lumps or pockets of flour. Scoop about 1/4 cup of batter into each muffin tin, or until 3/4 full.
In a blender, grind the oatmeal until the texture resembles cornmeal. Transfer to a large mixing bowl and add the brown sugar and cinnamon. Scoop about 3/4 tablespoon onto each muffin before baking.
Bake in your preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean with just a few crumbs. Enjoy!