Zucchini and Summer Squash Gratin with Parmesan and Fresh Thyme -

Ingredients

• 2 Tbsp. olive oil
• 2 medium sweet onions, thinly sliced
• salt and pepper
• 1 1/4 lbs. small, ripe tomatoes, cored and cut into 1/4 inch slices ( I used Roma tomatoes.)
• 3/4 lb. (about 2 small) zucchini cut into 1/4 inch slices on the bias
• 3/4 lb. (about 2 small) yellow summer squash, cut into 1/4 inch slices on the bias
• 3 Tbsp. olive oil
• 1/4 cup fresh thyme leaves
• 1 tsp. kosher salt, divided
• 1 1/4 cup grated Parmesan cheese