Preheat oven to 450 degrees. Coat a large baking pan with olive oil cooking spray.
In a large bowl, toss together eggplant, zucchini, squash, and onions with 1½ tablespoons olive oil.
Arrange on a baking sheet. Make a little room on one side of pan and add tomatoes and whole garlic cloves. Spray top of tomato mixture with a little olive oil cooking spray and toss to coat. Sprinkle the entire pan with salt and pepper.
Roast in oven for about 15-20 minutes until the eggplant is tender.
First transfer roasted tomatoes and garlic to a large bowl and add Italian seasoning. Mash together tomatoes and garlic with the back of a spoon. Make sure to break up garlic. Next, add roasted vegetables and toss in tomato mixture. Season with more salt and pepper, if desired.
Transfer into a serving dish, if desired. Top with 3 tablespoons of fat-free feta cheese. Or, dish out each serving and top each with a little cheese.