Preheat oven to 450°F. Put a large pot of water on to boil. Set a large bowl of ice water near the stove.

Melt 1 tablespoon butter in a small bowl in the microwave, about 30 seconds. Stir in ½ cup panko; set aside.

Cook 3 pounds asparagus in the boiling water until bright green, about 1 minute. Drain and transfer to the ice bath. Let cool for 5 minutes, then drain and pat dry. Arrange the asparagus in a 9-by-13-inch baking dish.

Heat the pot over medium-high heat. Add the remaining 2 tablespoons butter and stir until melted. Add 1 tablespoon garlic and cook, stirring, until fragrant, about 1 minute. Add 2 tablespoons flour and cook, stirring, for 30 seconds. Gradually whisk in 2 cups milk. Bring to a boil, whisking constantly. Continue cooking and whisking until the mixture thickens, about 5 minutes. Remove from heat. Stir in 5 ounces cream cheese, ½ cup mozzarella and 1 teaspoon salt. Pour the cheese sauce over the asparagus and stir to coat.

Sprinkle the reserved panko mixture on top. Bake until the asparagus is tender, 12 to 15 minutes.