Place butter inside a 9-inch cast iron skillet or pie plate, then place it in the oven on the center rack and turn it on to 450 degrees F.
While the oven preheats, mix together the eggs, pumpkin puree, milk, vanilla, maple syrup, oat flour, cinnamon, ginger, cloves and salt. I like to do this in a blender or in a bowl with an immersion blender, but you can also use a whisk. Just be sure no lumps remain.
When the oven is preheated, check to make sure the butter is melted. I like to let it go until it starts to brown and smell nutty, but that step is optional. Remove the skillet from the oven, pour the batter inside, then place it right back in.
Lower the oven temperature to 425 degrees, then bake for 15-20 minutes until it's puffed up, no longer jiggly and browned around the edges.
Slice into wedges and serve immediately with more butter and maple syrup on the side.