Cook pasta as directed on package; drain.

Meanwhile, melt 2 cups of the butter in large saucepot on medium-low heat. Add combined flour, salt and pepper; cook 2 to 3 min. or until thickened and bubbly, stirring constantly. Gradually stir in milk; cook until mixture just comes to boil and thickens, stirring frequently. Add Cheddar cheese and cream cheese; cook until melted, stirring frequently. Toss with pasta.

Melt remaining 2 cups butter. Mix with cracker crumbs and herbs.

For each serving: Spread about 1/3 cup chorizo onto bottom of 5-inch crock; top with 1/2 cup queso blanco cheese, 1 cup of the pasta mixture and about 3 Tbsp. crumb mixture. Bake in 300ºF-convection oven 10 min. or until bubbly and lightly browned. Top with additional 1 Tbsp. chorizo.