Preheat oven to 400 degrees Fahrenheit.

In a skillet over a medium flame, sauté onion in oil until soft and starting to brown. Add beef and cook until no longer pink, using a large spoon to break up into small pieces while cooking.

Season meat with 3/4 teaspoon salt and 1/4 teaspoon pepper.

While meat is cooking, wash zucchini, cut off the tops and bottoms, and spiralize.

In a large bowl or container, mix tomato sauce with remaining salt and pepper, garlic powder, onion powder, red pepper, and oregano (or use store-bought marinara sauce).

Place zucchini, meat, and tomato sauce in a 9 x 13-inch pan or Pyrex and mix until combined.

Bake uncovered for 30–40 minutes.