Preheat the oven to 350 degrees F.
Heat an oven-safe skillet (about a 10-inch) over medium-low heat. Add 1 ½ tablespoons butter and once melted, add in the shallots and mushrooms with a pinch of salt and pepper. Stir in the garlic. Cook until softened, about 5 minutes.
While the onions are cooking, whisk together the eggs, salt and pepper. Stir in the 2 to 3 cups greens, pasta and parmesan until combined.
Add the remaining 1½ tablespoons of butter to the skillet. Pour the egg mixture into the skillet. Use a spatula to stir and even everything out. Let it cook for 5 minutes.
Place the skillet in the oven and bake for 10 to 15 minutes, or until the center is set.
While the frittata bakes, whisk together the olive oil and lemon juice with a pinch of salt and pepper. Toss the greens with the olive oil + lemon juice and toss.
Remove from the oven and serve with the dressed spring greens and extra parmesan!