Spinach-Zucchini Frittata

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.

Heat butter and oil in a skillet over medium heat; stir in spinach, scallions, and zucchini. Saute until zucchini has softened, 7 to 10 minutes. Remove from heat and squeeze vegetables to remove as much moisture as possible. Allow to cool.

Meanwhile whisk eggs in a large bowl. Add Parmesan cheese, oregano, nutmeg, and pepper. Stir in cooled vegetables. Pour egg mixture into the prepared baking dish.

Bake in the preheated oven until eggs are set and the top is puffed and golden, about 30 minutes. Allow to cool. Cut into 8 squares and serve warm or at room temperature.