Prepare Oven & Roast Peppers: Position a rack in the center of your oven and preheat to 400°F (200°C). On a baking sheet, toss the diced red and orange bell peppers and shallot with 1 teaspoon of avocado oil, the smoked paprika, oregano, black pepper, and lemon zest. Spread into a single layer. Roast for 10–12 minutes, until the vegetables are tender and lightly browned at the edges.

Adjust Oven & Prep Pan: Once the vegetables are done roasting, reduce the oven temperature to 375°F (190°C). Lightly grease an 8-cup muffin tin with non-stick cooking spray or a very thin layer of oil.

Sauté Aromatics: While the peppers roast, warm the remaining 1 teaspoon of avocado oil in a 10-inch skillet over medium-high heat. Add the chopped mushrooms and cook, stirring occasionally, for 4–5 minutes until they release their moisture and begin to brown. Add the packed spinach and minced garlic, stirring continuously for 1–2 minutes until the spinach has fully wilted. Remove from heat.

Create the Egg Base: In a large mixing bowl, vigorously whisk the whole eggs, egg whites, milk, garlic powder, onion powder, and nutritional yeast (if using). Whisk for about 1 minute until the mixture is uniform, pale yellow, and slightly frothy.

Combine & Fill: Gently fold the roasted pepper mixture and the sautéed mushroom/spinach mixture into the egg base until just combined. Carefully pour the mixture evenly among the 8 prepared muffin cups, filling each about three-quarters full.

Bake: Transfer the muffin tin to the oven and bake for 12–16 minutes. The muffins are ready when they are puffed and golden, and a toothpick inserted into the center comes out clean.

Cool & Serve: Allow the egg muffins to cool in the tin for at least 5 minutes (they will deflate slightly as they cool). Run a thin spatula around the edges to loosen, then remove. Garnish with fresh chives and serve warm.