Melt butter in a large skillet over medium heat.

Add crushed and minced garlic to the melted butter and saute for 1-2 minutes until fragrant.

Add the white and light green parts of the leek and saute until softened.

Add flour, nutmeg, and pepper to the skillet and stir until well incorporated, cooking for 1-2 minutes until the flour is pale golden.

Slowly add milk while whisking constantly to prevent lumps.

Add cream cheese and mix until smooth.

Bring the mixture to a boil, whisking constantly, until it thickens.

Add spinach and artichoke hearts to the thickened sauce.

Cook until the spinach wilts, then remove from heat.

Season with salt and pepper to taste.

Preheat oven to 350F.

Pour the spinach and artichoke mixture into a baking dish.

Combine panko bread crumbs, parmesan cheese, and softened butter.

Sprinkle the bread crumb mixture over the spinach and artichoke mixture.

Bake for 30 minutes, or until the topping is browned and the sauce is bubbling.