Preheat oven to 350 degrees and butter a 13x9 in casserole dish
Cut the top and bottom off your butternut squash and peel, then cut in half and clean the seeds out. Using a mandoline or a very sharp knife cut into ¼ inch slices
In a saucepan, melt 2 tablespoons of butter, add the chopped garlic and cook for two minutes then whisk in 2 tablespoons of flour until combined and add the milk
Once combined add the cheese and stir until melted, then add the sage, pesto and salt and pepper to taste
Layer the squash first and top with ⅓ of the cream sauce, continue layering squash and sauce until all of the sauce is gone, making the top layer sauce
Mix the cheese and breadcrumbs for the topping and stir in the melted butter, crumble evenly over the casserole
Cover with tin foil and bake for 50 minutes or until fork tender, then uncover and cook another 10 minutes to brown the top
Notes
I used 2% milk to make this slightly healthier and because that is the type of milk we always have in the fridge, feel free to do the same.
This is a rather rich dish the nutrition is for ⅛th of the casserole which I think would be enough to satisfy along with other thanksgiving must haves.