Cut squash into 1/4-inch-thick slices; cut bell peppers into 1/4-inch strips. Cut onion in half lengthwise, and slice.
Sauté squash, bell peppers, onion, and garlic in 3 tablespoons hot oil in a large skillet 5 to 8 minutes or until crisp-tender.
Whisk together eggs and next 5 ingredients; stir in lobster, cheeses, and sautéed vegetables. Pour into a buttered 10-inch springform pan. Place pan on a baking sheet. Bake at 350° for 1 hour or until set. Let stand 10 minutes before serving. Garnish, if desired