For the squash, preheat oven to 375°F. Place the squash on a large baking sheet and drizzle with the olive oil. Season with salt, pepper, and sage. Toss until the squash is nicely coated with oil and bake for about 1 hour, until tender.
When the squash is done, let cool for a bit, then dice up about 1 ½ cups to mix into the grits.
For the grits, bring the water to a boil in a medium saucepan. Add the grits and bouillon, give it a stir, and reduce heat to a simmer. Cover and cook for about 50 minutes, stirring occasionally.
When the grits are cooked, season to taste with salt, and stir in the butter. Keep warm.
Heat the olive oil in a large cast iron skillet over medium-high heat.
Sauté the onion, shallots, and mushrooms for 2-3 minutes, until softened. Season with salt and pepper, to taste, and add about ¼ cup of the wine. Continue sauteing until most of the wine has evaporated.
When the grits are done cooking, add them to the cast iron skillet with the mushroom mixture. Season to taste with salt and pepper and stir about ¾ cup of the Parmesan cheese. Mix well.
Top with the remaining Parmesan and drizzle with a bit of truffle oil.
Transfer to a 375°F oven and bake for 10 minutes, until the cheese is golden brown.
