Butternut-Mushroom Polenta Casserole

Preheat oven to 425 F. Line a baking sheet with foil and spray with 1 tablespoon of EVOO. Place the 1 to 2 inch prepared butternut squash pieces on the pan and bake for 20-25 minutes. Once cooked set aside to cool to room temperature.
In a 6 quart sauce pan combine the milk, water, salt pepper and sage. Bring to a boil and slowly add the polenta stirring it thoroughly. Reduce to simmer and cook for 10-15 minutes until liquid is absorbed stirring to minimize sticking to the bottom.
Prepare a 9x13 casserole pan and pour the polenta into the pan. Smooth into an even bed with a spatula and allow to cool.
Slice mushroom to 1/4 inch thick pieces. Core the apple and chop to 1/2 inch dice. In a medium sauce pan over medium-high heat, add the 2 tablespoons EVOO. Add mushroom, thyme and apples and sautee for 10 minutes. Set aside to cool.
In a large food processor add the squash and mushroom mixture. Blend until the mushroom are finely chopped. Spread the mixture evenly over the polenta.
At this point you could prepare all of the above a day in advance and chill in the refrigerator.
Toast the hazelnuts until lightly browned. Set aside. Preheat oven to 325 F.
Slice the white and light green parts of the leeks into 1/4 inch slices. In a medium sauce pan over medium heat, add the remaining EVOO and leeks. Saute for 10 minutes until tender and lightly browned. Spread leeks over the squash mixture.
Top the casserole with the nuts and the cheese. Bake for 20 minutes at 325 F. Serve warm.