3 tablespoons all-purpose flour
1 teaspoon onion powder
1/2 teaspoon salt
1/4 teaspoon black pepper
8 ounces Gouda cheese, grated
4 ounces sharp Cheddar cheese, grated
4 ounces Swiss cheese, grated
1/2 cup grated Parmesan cheese
Heat broiler. Coat a 9 x 9-inch broiler-safe baking dish or six 1-cup ramekins with nonstick cooking spray.
Bring a large pot of lightly salted water to a boil. Add pasta and cook 11 minutes, following package directions. Drain and transfer to bowl.
Gradually add milk; whisk until smooth. Bring to a simmer over medium to medium-high heat, stirring, then add onion powder, salt and pepper. Simmer 3 minutes, then remove from heat.
Stir in Gouda, Cheddar, Swiss and 1/4 cup of the Parmesan until cheeses are melted and sauce is smooth.
In medium-size microwave-safe bowl, melt remaining 1 teaspoon butter. Stir in panko and remaining 1/4 cup Parmesan.