Grate zucchini and squash with a fine grater. Press between paper towels to remove excess moisture.
In a medium bowl, combine grated zucchini and squash and next 7 ingredients. Shape mixture into 2-inch patties, pressing together firmly.
In a large skillet, melt butter over medium heat. Cook squash and zucchini cakes 3 to 4 minutes per side or until lightly browned.
Place onto serving platter and serve with marinara sauce.