Mix together all ingredients for marinade: Olive oil, lemon juice, salt, pepper, oregano and thyme. Pour marinade mixture into a Ziplock bag, add chicken parts, seal bag and shake until chicken is thoroughly coated. Store in refrigerator for 4-6 hours or overnight.
Put chicken and marinade in a large bowl and add tomatoes, summer squash and onion. Mix together well.
Divide mixture into about 5 parts. Place onto sheets of aluminum foil and wrap tightly to create pouches. Don’t let the liquid leak out. Double wrap if needed.
Bake in the oven at 450 degrees Fahrenheit for 45 minutes. This is also delicious prepared on a covered grill, cooked for about 45 minutes on a medium heat (450, if you have a temperature gauge).