In a large pot, heat the 1 tablespoon oil over moderate heat. Add the squash, ½ teaspoon salt and the pepper. Cook, stirring frequently, until the squash is just tender and browned, about 5 minutes.
Add the pancetta and cook until it begins to crisp. Remove the squash mixture from the pan with a slotted spoon, leaving some drippings in the pan. In a medium saucepan, bring the broth to a simmer.
In the large pot, heat the remaining teaspoon of oil over low heat. Add the shallot and cook, stirring occasionally, until translucent, about 2 minutes. Add the rice to the shallots and stir until it begins to turn opaque, about 2 minutes.
Add the wine, sage and the remaining ¾ teaspoon salt to the rice. Cook, stirring frequently, until all of the wine has been absorbed. Add about ½ cup of the simmering broth and cook, stirring frequently, until it has been absorbed. The rice and broth should simmer gently; lower the heat if it bubbles more rapidly.
Continue cooking the rice, adding broth ½ cup at a time and allowing the rice to absorb it before adding the next ½ cup. Cook the rice in this way until tender, 25 to 30 minutes in all. The broth that hasn't been absorbed should be thickened by the starch from the rice. You may not need to use all the liquid, or you may need more broth or some water.
Stir in the squash and pancetta and additional salt and pepper to taste.