Preheat oven to 425℉ and grease or line a 12-cup muffin tin with paper liners.
In a large bowl, whisk together the 2 cups oat flour, ½ cup almond flour , 1 teaspoon baking soda, 1 teaspoon baking powder, ½ teaspoon sea salt, 1 ½ teaspoon ground cinnamon, ½ teaspoon ground nutmeg, ¼ teaspoon ground allspice, ¼ teaspoon ground ginger, and ¼ teaspoon ground cardamom.
In a small bowl, whisk together the 1 15-ounce can pure pumpkin puree, ½ cup granulated sugar, ½ cup maple syrup, ½ cup unsalted butter, and 2 large eggs until smooth and combined.
Add the wet ingredients to the dry ingredients and mix gently until just combined.
Using a ¼ cup measure, divide the batter evenly between the muffin cups, filling each cup nearly to the rim. Rest the batter for 15 minutes.
Bake the muffins at 425℉ for 5 minutes, then reduce the heat to 350℉ and bake 10-12 more minutes or until a toothpick inserted into the center comes out clean.
Let the muffins cool for 5 minutes in the muffin tin, then turn them out to a wire rack to cool completely.
Notes
Why the different temperatures? Starting muffins at a higher temperature (425°F) and then lowering it for the remainder of the baking time creates those beautiful, domed tops. Give it a try!
Make them with regular flour. If you don't need to keep gluten-free, make these muffins with 2 ¼ cups all-purpose flour or whole wheat pastry flour.
Sprinkle with sugar. For a little added sweetness, sprinkle coarse or granulated sugar over the tops of the muffins before baking.
Rest the batter. For the best results, let the batter rest in the tin for at least 15 minutes before baking. Full disclosure: I let my batter rest for about 35 minutes on my first recipe test because I had something else in the oven, and they turned out absolutely divine.
Fill up the muffin cups. These muffins turn out best when the muffin tin cups are filled nearly to the rim. Don't worry, they won't spill over when baking because of the high temperature at the start.
Brown the butter. Yes, I love browning butter as a base in so many recipes! It will add a rich, slightly nutty undertone to the finished product. Melt butter over low heat, swirling the pan occasionally, until it crackles and gives off a nutty aroma. Cool slightly before continuing with the recipe.
Use salted butter. For a little bit of sweet-salty, use salted butter rather than unsalted butter in the batter.