Preheat the oven to 325˚.

Heat the oil in a 12” non-stick skillet over med-high heat. Sauté the garlic, asparagus, mushrooms, and onion for about 3-4 minutes until just tender.

Reduce the heat to medium and pour in the eggs. Stir in the herbs and cheeses; season with salt & pepper.

Once the bottom is firm, use thin, nonmetallic spatula to lift frittata edge closest to you. Tilt skillet slightly toward you so that uncooked egg runs underneath. Return skillet to level position and swirl gently to evenly distribute egg. Continue cooking about 40 seconds, then lift edge again, repeating process until egg on top is no longer runny.

Transfer skillet to oven; bake until frittata top is set and dry to touch, 3-5 minutes, making sure to remove frittata as soon as top is just set. Run spatula around skillet edge to loosen frittata; invert onto serving plate. Serve warm, at room temperature, or chilled with a dollop of sour cream.