INGREDIENTS
2 cups
(1/4-inch-sliced) fennel
1 lb
Celery root
3 cloves
Garlic
1
Onion, sliced (1 1/2 cups), large
1 lb
Sweet potatoes
2 tsp
Thyme, fresh leaves
1
Kosher salt and freshly ground black pepper
1
Olive oil
2 1/2 cups
Breadcrumbs or panko, coarse fresh
2 tbsp
Butter
2 cups
Gruyere cheese, grated
1 cup
Heavy cream
2 cups
Chicken or vegetable stock or brother
1 pound yukon gold, peeled and sliced 1/4-inch thick