Make-Ahead Spinach and Mozzarella Breakfast Strata

Melt butter in a medium skillet over medium heat. Add onion and saute until soft about 5 minutes. Add herbes de Provence salt and pepper; continue to cook for 1 minute more. Stir in spinach remove from heat and set aside.

Spray the inside of a 3-quart (9x13-inch) baking dish with cooking spray. Layer the bottom of the dish with 1/3 of the bread cubes. Top with 1/3 of the spinach mixture and 1/3 mozzarella cheese. Repeat these layers twice more with remaining bread spinach mixture and cheese.

Combine eggs milk salt and pepper in a medium bowl. Whisk together until blended. Pour evenly over the bread and spinach layered in the baking dish. Cover with plastic wrap and chill for at least 8 hours up to 1 day.

Remove from the refrigerator 30 minutes before baking to allow pan to get to room temperature.

Meanwhile preheat the oven to 350 degrees F (175 degrees C).

Bake uncovered in the preheated oven until puffed golden brown and cooked through 45 to 55 minutes. Let stand at least 5 minutes before serving.