1Preheat oven to 375 degrees and spray a large casserole dish with nonstick spray. Heat oil in a large non-stick frying pan. Add the squash, garlic and thyme.
2Saute and stir just until the squash is starting to soften slightly. Don't overcook. Remove from heat and add tomatoes.
3Beat together the eggs, sour cream, cheeses and lemon juice in a medium sized bowl. Place 1/2 the squash in bottom of the casserole. Sprinkle on some salt and pepper, then spread 1/2 of the egg mixture over the top.
4Repeat with remaining squash and egg mixture. Top with additional feta and parmesan if desired. Bake 40 - 45 minutes, until the mixture is bubbling and slightly set. Serve hot.