Mushroom and Beet Green Frittata

5 shallots, peeled and thinly sliced
1 clove garlic, peeled and chopped
beet greens, stems removed and roughly chopped
1 1/2 cup mushrooms, sliced
2 tablespoons butter
6 eggs
2 tablespoons heavy cream
1/2 cup each loosely packed shredded gruyere and parmesan cheeses
salt and pepper to taste

Preheat your oven's broiler.

In a non-stick, oven-proof skillet, saute the shallots, garlic, greens and mushrooms over low heat. Meanwhile, whisk together the eggs, cream, and half of the cheese. Once the mushroom mixture has cooked, spread it evenly in the bottom of the pan and turn up the heat to medium high. If the mixture looks dry, add another tablespoon of butter at this point. Pour on the egg mixture and stir for about a minute. Then leave alone it to cook for a few more minutes. When it looks like things are pretty set on the bottom (I use a rubber spatula to gently lift the eggs and peak underneath), sprinkle the top with the remaining cheese, salt and pepper, and move the skillet under the hot broiler. Cook there for 3-5 minutes until the top has set and begun to brown.