Puree the tomatoes in a food processor (yields 1 1/2 cups of sauce). Stir in the onion, 1/2 tsp. salt, and maple syrup.
Pour the tomato mixture into a 13x9 inch pan and evenly distribute the sauce across the bottom of the pan.
Use a food processor or mandoline to thinly slice the eggplant, zucchini, and squash. Place them in a spiral pattern as seen in the photo above. Start on the outside of the pan and work your way to the middle. You may have some extra vegetables that don’t fit in the pan depending on how tightly you arrange them.
Sprinkle the olive oil, 1/2 teaspoon salt, and paprika over the vegetables.
Cover the pan with foil and bake for 30 minutes. Raise the temperature to 425 degrees and remove the cover. Bake for another 5 minutes. Keep an eye on it so the vegetables don’t turn to mush.