In an ovenproof skillet with a tight-fitting lid, add the pancetta and cook over medium heat until browned and crispy, about 8 minutes. Remove to a paper towel-lined plate to drain.
To the pancetta drippings, add the butter and melt. Add the garlic and onion and cook until just translucent, about 4 minutes. Add the sage and thyme, then stir in the rice and cook, stirring, until the rice is well coated in the butter and pancetta drippings. Add the squash, broth and wine, then sprinkle with salt and pepper and stir. Bring to a simmer, cover with the lid and place in the oven. Bake until the liquid is absorbed and the rice is tender, 45 to 60 minutes.
Carefully remove from the oven. Add the Parmesan, parsley and lemon juice, then stir until creamy. Sprinkle with the crispy pancetta and some more grated Parmesan and chopped parsley.