Step 1

Add 2 tablespoons of butter to a 3-quart or larger saucepan and set it over medium-low heat. When the butter is melted, add 1 1/2 tablespoons of all-purpose flour. Cook the flour and butter with a wire whisk, stirring constantly, for 1 minute.

Step 2

Slowly add 1 1/2 cups of milk, whisking constantly as you pour it into the saucepan. (Adding it slowly will prevent lumps.) Add 1/4 teaspoon each red pepper flakes, salt, and pepper and bring the sauce to a simmer.

Step 3

Continue to let the sauce simmer over medium-low heat, whisking frequently, until the béchamel is thickened and does not taste like raw flour, about 5-6 minutes. (The sauce should be thick enough to coat a spoon; see photos above.)

Step 4

Remove the saucepan from the heat and add 1/2 cup grated parmesan. Whisk until the cheese is melted, then taste and add more salt and pepper if you like. Cover and set aside.

Step 5

Heat the oven to 375 degrees F (190 degrees C) Add 2 tablespoons of olive oil and 4 or 5 chopped cloves of garlic to a large, heavy bottom saucepan, dutch oven, or cast iron braiser. Set the pan over medium heat and cook, stirring, until the garlic is soft and fragrant, about 30 seconds.

Step 6

Add the spinach to the garlic and oil one generous handful at a time. Let each addition wilt before adding the next. Add 1/4 teaspoon crushed red pepper (optional) and about 1/2 teaspoon each salt and pepper. Continue to cook, stirring frequently, until most of the liquid from the spinach has evaporated. This could take anywhere from 3 minutes to 10 minutes depending on the humidity in the air and the water content of the spinach.

Step 7

Add 2 tablespoons of lemon juice and a 14-ounce jar of artichoke hearts. Cook for another 2-3 minutes.

Step 8

Reduce the heat to low and add the béchamel sauce, 2 tablespoons of mustard, and 4 ounces (a heaping 1 cup) of grated mozzarella cheese. Use a wooden spoon or spatula to stir until all the cheese has melted. Taste and season with more salt and pepper if desired then stir in the chicken.

Step 9

Spread the mixture into a 9-inch square baking dish and sprinkle with the remaining 4 ounces (a heaping 1 cup) mozzarella cheese and 1/4 cup parmesan.

Step 10

Melt two tablespoons of butter in the microwave and stir in 1 cup of panko bread crumbs until the bread crumbs are all moistened. Sprinkle the buttery crumbs over the casserole in an even layer. (At this point the casserole can be refrigerated for up to 24 hours.)

Step 11

Bake at 375 degrees F (190 degrees C) for approximately 30 - 40 minutes or until the topping is golden brown, and the edges of the casserole are bubbling.

Step 12

Allow the casserole to rest for 10 minutes, then serve.