2 tbs. unsalted butter
1 medium yellow, sweet onion
6 cups 1-inch-diced peeled, seeded butternut squash
2 medium cloves garlic, sliced
1/2 cup dry white wine
4-6 cups chicken broth
2 1/4 cups packed, grated gruyere
1/4 cup grated parmesan
kosher salt and freshly ground black pepper
6 slices rustic French bread, cut 1/2 inch thick
1 tsp. minced fresh sage