Preheat oven to 400 degrees. Arrange squash in a single layer on a baking sheet. Drizzle with olive oil, tossing to coat. Bake for 15 minutes or until squash is tender. Remove from pan, stir in garlic; set aside.
Heat a large saucepan over medium heat. Add pancetta, cook 5 minutes or until browned, stirring frequently.
Add onion, cook 3 minutes or until tender, stirring occasionally.
Add rice, cook 2 minutes, stirring constantly.
Add wine, cook 1 minute or until liquid is nearly absorbed, stirring constantly.
Add broth, 1/2 cup at a time, stirring constantly until each portion of broth is absorbed before adding the next (about 20 minutes total).
Stir in squash, thyme, lemon zest, salt and pepper. Just before serving, stir in cheese.