Zucchini and Caramelized Onion Quiche

INGREDIENTS

1/2 14.1 ounce package

refrigerated pie dough (such as Pillsbury)

1 tbsp

olive oil

4 cups

(1/8-inch-thick) slices zucchini

garlic cloves, minced

3/4 tsp

kosher salt, divided

1/2 cup

finely chopped Basic Caramelized Onions

1 cup

1% low-fat milk

1 1/2 tbsp

all-purpose flour

1/2 tsp

freshly ground black pepper

large eggs

2 oz

Parmigiano-Reggiano cheese, grated (about 1/2 cup)