Preheat oven to 350 degrees F. Cut squash, zucchini, and pattypan squash into circles and slice onion. Set out on a roasting tray and scatter thyme leaves over the top. Drizzle with olive oil and season with salt and pepper. Roast in the preheated oven for 15 to 20 minutes, until golden brown and fragrant.

While the vegetables roast, start the risotto. Set a large, heavy-based pot over medium heat. Pour a 3-count of oil (about 3 tablespoons) into the pot and fry the sage leaves until they are crispy and crackly. Drain leaves on paper towels and set aside. Add onion to the pot and saute until fragrant and slightly translucent. Add rice and cook for 2 to 3 minutes over medium heat as you stir with a wooden spoon. Add the wine; cook until mostly evaporated. Begin adding vegetable broth, a little at a time, allowing the rice to absorb the broth each time before adding more. Continue to do this until the rice is tender but still has a little bite. (Add water, if necessary, if you use all the vegetable broth before the rice is done.) To finish, add butter and Parmigiano.