Lightly grease or line a standard 12-cup muffin pan with liners.
In a medium bowl, whisk together the dry ingredients.
In another bowl, whisk together the eggs, buttermilk, and oil. Stir the wet ingredients into the dry ingredients, then stir in the grated carrots.
Scoop the batter into the prepared pan, filling the muffin cups almost to the top.
Preheat the oven to 400°F. Rest the batter while the oven heats, then bake the muffins for 20 to 25 minutes, until a toothpick inserted into the center of a muffin comes out clean.
Cool the muffins in the pan for 5 minutes, then turn them out to cool completely.
Notes
Use room temperature ingredients. Bring the buttermilk and eggs to room temperature before baking to ensure the muffins rise especially well.
Don’t overmix! For the tenderest muffins, stir gently together the batter until everything is just combined.
Rest the batter. Make sure to let the muffin batter rest in the muffin tin for up to 20 minutes (while the oven heats usually works great), so fully hydrate the oat flour.
What size to make the muffins? I used a ¼ cup measure to scoop the batter into the tin so that each muffins would be about the same size.
Use gluten-free flour. Skip the oat flour and use a 1:1 gluten-free all-purpose blend (my homemade gluten free flour blend always works perfectly).
Dairy-free: You can use dairy-free milk for the buttermilk, or just use water.
Make them egg-free: Substitute 1 mashed banana or 2 flax eggs for the eggs.