Bring 1 quart stock plus 1 cup water to a simmer in a sauce pot then reduce heat to low.
Heat a medium skillet over medium to medium-high heat with olive oil. When oil ripples, add the onions and garlic and soften 2 to 3 minutes. Add rice and toast 2 to 3 minutes more. Add wine and cook it out completely, stirring occasionally, 2 to 3 minutes. Ladle in stock in intervals, a couple of ladles at a time. Allow liquids to evaporate each time. Risotto will cook 18 minutes, total, from the first addition of liquid. Defrost the squash in your microwave in a dish to collect any liquids and stir in squash the last 3 minutes of cook time, season with nutmeg, salt and pepper to taste. In the last minute of cooking time, stir in butter in small pieces, sage leaves and cheese, serve.