Zucchini Gratin

INGREDIENTS

5 tbsp

butter

1 lb

yellow onions, cut in 1/2 and sliced (about 3 large)

2 lb

zucchini and/or yellow squash, sliced 1/4-inch thick (about 4 zucchini)

3/4 tsp

kosher salt (use 1/2 teaspoon if using table salt)

1 tsp

freshly ground black pepper

1/4 tsp

ground nutmeg

2 cloves

garlic, finely minced or pressed

2 tbsp

all-purpose flour

1 cup

milk

6 tbsp

Italian style bread crumbs

3/4 cup

grated Gruyere

olive oil