Spinach Casserole

Preheat the oven to 350°. Combine 1/2 cup of fried onions and the panko breadcrumbs in a small bowl; set aside.

Heat a large skillet or Dutch oven over medium heat, then add the olive oil. Add the spinach (in batches, if needed). Cook, stirring occasionally, until wilted, about 5 minutes. Transfer to a heat safe bowl and set aside.

Add the butter in the same skillet. Let it melt until bubbly and golden. Add the garlic and flour and stir constantly with a wooden spoon, for 2 minutes.

Whisk in the milk, salt and pepper. Cook, stirring frequently, until the mixture thickens, about 5 to 7 minutes.

Reduce the heat to low and stir in the cream cheese until completely combined. Add the gruyère in three batches, making sure cheese is completely incorporated before adding the next batch. Stir in parmesan. The mixture will be very thick and will give a lot of resistance when stirring.

Add the spinach with juices back to cheese sauce, stirring until well combined. Add the remaining 1/2 cup of fried onions.

Transfer the mixture to an 8-by-8-inch baking dish. Sprinkle with the fried onion and panko mixture.

Bake until the casserole is bubbling and the topping is golden brown, about 30 to 35 minutes. Let sit for at least 10 minutes. Top with lemon zest just before serving.