Prep the pan and oven. Heat the oven to 375°F (190°C).
Grease a 12-cup muffin tin well or line with parchment liners. Greasing thoroughly helps the muffins release cleanly.
Drain your veggies. If using zucchini, grate it and squeeze it in a clean towel to remove excess water. Too much moisture can make the muffins soggy.
Mix the wet ingredients. In a large bowl, whisk eggs, Greek yogurt, and milk until smooth.
The yogurt keeps the texture tender and adds a gentle tang.
Add the dry ingredients. Whisk in oat flour, baking powder, salt, pepper, garlic powder, and smoked paprika. Stir just until combined. The batter will be slightly thick.
Fold in the add-ins. Stir in zucchini or spinach, bell pepper, sausage or beans, cheese, and green onions.
Taste a small dab and adjust salt if needed.
Fill the muffin cups. Divide the batter evenly among the 12 cups. They should be about 3/4 full.
Bake. Bake for 18–22 minutes, until the tops are set and lightly golden, and a toothpick in the center comes out clean. Don’t overbake or they’ll turn dry.
Cool and release. Let the muffins rest in the pan for 5 minutes, then run a small knife around the edges and lift them out to finish cooling on a rack.
Serve or store. Enjoy warm, or cool completely before storing.
A little hot sauce or salsa on top is great.