Place zucchini in a colander set in a large bowl or in the sink. Press firmly to remove excess water.Advertisement
In a large skillet heat butter over medium heat. Add onion and garlic. Cook and stir for 5 minutes. Add zucchini. Cook, stirring occasionally, for 15 minutes or until zucchini is very soft. Stir in spinach. Cook and stir 2 minutes more. Cool slightly. Divide among 4 half-pint airtight freezer containers leaving 1/2-inch headspace. Seal and freeze up to 3 months. Thaw at room temperature or in the refrigerator. Place in a saucepan and warm through before using. Use to top chicken, fish, cheese-topped bruschetta, soups or pasta dishes.