Make-Ahead Frittata Squares Recipe

Ingredients

• Butter (for the baking dish)
• 2 tablespoons olive oil
• 1 pint cherry tomatoes
• 1 bunch scallions, thinly sliced
• 5 ounces (about 3 1/2 packed cups) baby spinach leaves
• 1/2 cup whole milk
• 1/2 cup sour cream
• 12 large eggs
• 3/4 teaspoon salt, divided
• 1/8 teaspoon freshly ground black pepper
• 1 cup (about 5 ounces) crumbled feta cheese
• 3 tablespoons chopped fresh parsley