For a vegetarian main or a hearty lunch.
Preheat oven to 400° Fahrenheit. Lightly grease a baking sheet.
Season the squash slices with half of the garlic salt and pepper. Arrange squash evenly on the baking sheet and bake in the oven for about 20 minutes. Remove from the oven and set aside.
Season the sliced tomatoes with the remaining garlic salt and pepper and set aside.
Place about 1/3 of the diced tomatoes in the bottom of a large skillet. Add half of the squash and half of the tomato slices. Top with 1/3 of the diced tomatoes and half the Italian cheese blend. Repeat the layering and top everything with Parmesan.
Cover tightly and simmer over low heat for about 25 minutes.
In the meantime, cook spaghetti according to package instructions and drain. Add squash mixture to spaghetti and toss well.