Scalloped Sweet Potatoes and Apples

INGREDIENTS

3 tbsp

unsalted butter

1/2

medium onion (diced)

2 tbsp

corn starch or potato starch

1 cup

chicken or vegetable stock

2 cups

milk

1 tsp

Kosher salt

1/2 tsp

black pepper

2 tsp

fresh thyme leaves (divided and 1 teaspoon minced)

3 lb

sweet potatoes (peeled and sliced into 1/8-inch rounds (I used a mandoline))

1 lb

apple (peeled and thinly sliced)

2 cups

shredded sharp cheddar cheese (divided. I used Cabot Seriously Sharp)