Blanch the asparagus: Bring 4 quarts of water, and 1 teaspoon of salt to a boil. Add the asparagus and set a timer for 2-3 minutes. Meanwhile, prepare a bowl with ice cold water. When the timer is up, Remove the asparagus from the boiling water, and plunge it into the ice water to stop the cooking process. Leave the asparagus in the ice water for 5 minutes, then drain and dry with paper towels. Cut into 2 inch pieces.
Preheat the oven to 350°F (180°C), or 160°C fan oven. In a bowl, combine the breadcrumbs with parmesan, and set aside.
Make the sauce: Melt the butter in a skillet over medium heat, and add the mushrooms. Season with salt and pepper and cook for 2-3 minutes or until tender. Add garlic and cook for 30 seconds, then add flour and cook for 30 more seconds.
Gradually add milk and whisk until heated through. Then add in the cream cheese and mozzarella and nutmeg. Remove from heat and stir to melt the cheeses.
Add blanched asparagus to the sauce and stir to combine. Transfer to a 9×13 inch (approx 22 x 33 cm) casserole dish if the dish you’re using is not oven-proof. Sprinkle the panko parmesan mixture over the top.
Bake in the preheated oven for 15 minutes, then place under the broiler until the top is golden brown.
