Position a rack in the upper third of the oven and preheat to 350ºF. Line 12 standard-sized muffin cups with paper liners or rub with room temperature butter or coconut oil.
In a large bowl, whisk together the egg, pumpkin puree, olive oil, coconut sugar, maple syrup, and sour cream until smooth.
Place a strainer over the bowl and sift in the oat, sweet rice, millet, and tapioca flours with the baking powder, baking soda, salt, and spices.
Whisk the batter until smooth. Let sit for a few minutes to thicken (this makes it easier to scoop into the cups) and use a large spoon or spring-loaded ice cream scoop to fill the muffin cups almost to the top. Gently smooth the tops.
Mix together the maple sugar and cinnamon and sprinkle over the tops of the muffins.
Bake the muffins until the tops are domed, spring back when poked, and a toothpick inserted in the middle of a muffin comes out with moist crumbs, 20 – 30 minutes.
Let the muffins sit for a few minutes to firm up, then carefully remove them to a wire rack to let them cool.
They are most delicious within a few hours of baking, but will keep, covered, at room temperature for a day or too. Refrigerate or freeze for longer storage.
For eggs, sub 2 tablespoons flaxseed meal (14 g) mixed with 6 tablespoons (90 g) hot water. Let sit until thick, 10-20 minutes.
For olive oil, sub another neutral oil such as sunflower or grapeseed
For coconut sugar, sub by weight maple sugar, date sugar, or granulated or brown sugar.
For dairy-free, use rich coconut yogurt, vegan sour cream, or dairy-free Greek yogurt in place of the sour cream
For oat flour, substitute by weight sorghum flour, teff flour, or chestnut flour.
For sweet rice flour, substitute by weight GF AP flour (such as Bob's Red Mill 1 to 1) or cassava flour.
For millet flour, substitute by weight sorghum flour, teff flour, or buckwheat flour.
For golden pumpkin spice blend, substitute store-bought pumpkin pie spice or use the following quantities for a single batch of muffins:
1 1/8 teaspoons ginger
1 teaspoon cinnamon
1/4 + 1/8 teaspoon nutmeg
1/4 + 1/8 teaspoon turmeric
1/8 teaspoon allspice
Vegan GF Pumpkin Muffins:Omit the egg and use 2 tablespoons flaxseed meal (14 g) mixed with 6 tablespoons (90 g) hot water. Let sit until thick, 10-20 minutes, stirring once or twice, and add to the wet ingredients. Use rich coconut yogurt, vegan sour cream, or dairy-free Greek yogurt in place of the dairy sour cream.To Freeze:Place muffins on a small baking sheet and freeze until firm, 1-2 hours. Transfer to a freezer-safe container or zip-top freezer bag and store for up to 2 months. To serve, heat in a 325º oven or toaster oven until warmed through.Nutrition values are for 1 of 12 servings.