Cut the vegetables into uniform sizes. You will want to pack them in tightly in the pattern that you choose, since they will shrink slightly while cooking. Once you have all the vegetables cut into equal thickness and diameter, I find it helps to “dry fit” them into the pan just to see if you need to add more or less of any one type.

Using an 8- to 10-inch / 20 to 25 cm round baking pan or deep pie dish, begin by adding the arrabbiata sauce to the bottom of the pan. Then add the zucchini, squash, and eggplant in a layered or circular pattern. Once you have a uniform pattern, push the roasted pepper slices in between the vegetable slices 
to fill the gaps.

Preheat the oven to 325°F / 160°C.

Mix the oil with the pesto and drizzle over the vegetables. Fill the gaps between the layers with drained sun-dried tomatoes.

Place the pan in the oven and roast for 1 hour, then check the tenderness of the vegetables and overall browning. You can add more time, checking in 10-minute increments. If you think the dish is becoming too browned, you can finish the final cook time by covering the pan with aluminum foil. Serve warm with grilled meat or sausage if you wish.