Heat the broth in a medium saucepan on medium heat until it simmers. Reduce heat to low, cover and continue to simmer.
Cut the squash into ½ inch cubes.
Heat the oil in a Dutch oven or other heavy-duty pot on medium heat. When the oil shimmers, add the shallots and sauté until translucent and aromatic, about 2 minutes.
Add the garlic, ½ teaspoon of minced sage leaves, and diced squash. Continue to sauté on medium heat for 6 to 8 more minutes, stirring occasionally.
Add the rice, stirring frequently, until the rice is lightly toasted, 1 minute.
Reduce the heat to medium-low. Add salt, pepper, and ½ cup of the vegetable broth, stirring every 30 seconds, until the broth is absorbed into the rice.
Continue by adding ½ cup of broth at a time, again stirring every 30 seconds, until the broth has been absorbed. This step should take about 20 minutes, until the squash is soft and creamy and the rice cooked through, but still al dente. Times may vary.
Remove the risotto from the heat, and stir in the butter and Parmesan cheese.
Garnish with the remaining ½ teaspoon of minced sage leaves and serve hot.