Preheat and prep the tin: Heat the oven to 375°F (190°C). Grease a 12-cup muffin tin very well with oil or cooking spray. Silicone liners work great if you have them.

Chop your veggies small: Dice everything into pea-sized pieces. Smaller pieces cook faster and distribute evenly in each muffin.

Sauté moisture-heavy veggies: Heat 1 tablespoon olive oil in a skillet over medium heat. Sauté onions, mushrooms, or zucchini for 3–4 minutes to cook off moisture. Add garlic for the last 30 seconds. Remove from heat and let cool slightly.

Whisk the egg base: In a large bowl, whisk eggs, milk, salt, pepper, garlic powder, and red pepper flakes if using. Stir in herbs.

Add fillings: Fold in the chopped veggies (including the sautéed ones) and cheese, if using. Don’t overmix—just combine.

Fill the muffin cups: Divide the mixture among the 12 cups, filling each about 3/4 full. Stir the bowl between pours to keep fillings evenly distributed.

Bake: Place the tin on the center rack and bake for 14–18 minutes, or until the muffins are puffed and the centers are just set. A toothpick should come out mostly clean.

Rest and release: Let them cool in the pan for 5 minutes. Run a thin spatula or butter knife around the edges to release. Transfer to a rack to cool.

Serve or store: Enjoy warm, or cool completely for meal prep. Add a sprinkle of herbs or hot sauce if you like.