1. Preheat oven to 375° F. Line a 12-cup muffin pan with parchment paper liners.
2. Whisk the almond flour, baking powder, salt, and herbs, breaking up any clumps. Stir in the oats.
3. In a separate bowl, whisk the eggs, then add the milk and butter; stir well to combine.
4. Add the wet ingredients to the dry ingredients and stir well until completely combined. Add the cheese and your chosen add-ins, stirring to distribute all ingredients evenly.
5. Divide the batter equally among the 12 muffin cups (they will be full). Tap the muffin tin on the counter a few times to settle the batter, then transfer to the oven.
6. Bake for 25-30 minutes, until the tops are golden and a toothpick inserted into the middle of a muffin comes out clean. Allow to cool for 10 minutes before serving.
7. Store any leftovers in an air-tight container in the refrigerator for up to 3 days or in the freezer for up to a month. To reheat, warm in the oven or toaster oven at 300° F for about 10 minutes before enjoying (thaw before warming if frozen).