Preheat oven to 425°F.
Slice squashes in half lengthwise and scoop out seeds. Place cut side down on a large baking sheet and drizzle with tbsp olive oil. Add salt and pepper. Roast for 40 mins, until edges are brown and flesh is easily pierced. Keep warm until read to serve.
Heat a large saucepan over medium heat. Add 1 tbsp olive oil and add shallots and garlic. Cook until translucent, 2-3 mins.
Stir in rice and cook for 30 sec until fragrant. Add broth and bring to a boil. Reduce the heat, cover, and simmer for 40 mins until most of the liquid is absorbed, adding spinach on top when there is about 15 mins remaining.
When the rice is cooked, remove from heat and fluff with a fork. Add sage, vinegar, cranberries, and walnuts.
Remove squashes from oven and add rice mixture to each one. Top with feta.
