Boil potatoes in a large deep sauce pan for 3-5 minutes. Cover and remove from heat. Melt 1 T butter and saute onion until softened, 5 minutes. Add remaining butter and flour and stir, cooking for 1 minute. Squeeze out roasted garlic into pan, season with salt and pepper, and stir into roux. Pour in 1 cup cream and stir. Cook until sauce thickens. Add cheeses. Add more cream if sauce seems to thick and cook until smooth. Drain potatoes and place in a greased 1 1/2 quart shallow baking dish. Pour cheese sauce over all. Stir gently to combine. Season again if desired
Bake at 350 for 45 minutes or until set and golden. Serves 4-6
Notes
*roast garlic wrapped in foil and drizzled with olive oil at 400 for 45-60 minutes. Can be roasted in advance and stored in refrigerator