1 large garlic clove, cut in half
1 pound potato, about 1/4 inch thick
1 pound winter squash, such as butternut or winter sweet, peeled seeded and sliced about 1/4 inch thick pieces
1 teaspoon fresh thyme leaves
1 teaspoon chopped fresh sage
1 cup, tightly packed, grated Gruyère cheese
Salt to taste
Freshly ground pepper
2 1/4 cups low-fat milk