Mini Hash Brown Frittatas

Name: Mini Hash Brown Frittatas
Cook time: 1 h 15 min
Total time: 1 h 15 min
Cuisine: American, Mediterranean
Ingredients: Baking spray with flour; 1 (20-oz.) pkg. refrigerated shredded hash browns (such as Simply Potatoes); 10 ounces sharp Cheddar cheese, shredded (about 2 ½ cups), divided; 1 (10-oz.) pkg. frozen chopped spinach, thawed; 1 tablespoon unsalted butter; 1 small onion, minced (about 1 cup); 6 large eggs; .75 cup half-and-half; 2.5 teaspoons kosher salt; .5 teaspoon black pepper; .5 cup quartered cherry tomatoes (from 1 pint tomatoes)