Preheat oven to 400 degrees.
Cook pasta until ‘al dente’, or firm, about 2 minutes less as directed on package and drain. It is important not to fully cook pasta, as it will continue to cook in the oven.
In a large pan, melt 4 tablespoons of butter over medium heat. Whisk in flour, stirring until bubbly and fragrant, about 2-3 minutes.
Whisk in milk, stirring until thickened.
Stir in cream cheese, whisking until cheese has melted into the sauce.
Add shredded cheeses. Stir until well incorporated, and cheese is melted. Season with onion powder and salt as needed.
Add pasta to cheese sauce, tossing until pasta is well covered. Pour into a casserole dish or into individual ramekins.
In a frying pan, melt the remaining 8 tablespoons of butter. Once melted, stir in Panko until butter is absorbed to create topping.
Sprinkle Butter Crunch Topping over the top of Mac and Cheese. Place into oven and bake for 20 minutes, or until topping is browned, and sauce is bubbly.