Cook pasta as directed on package.

Meanwhile, saute onions in 2/3 cup butter until caramelized; set aside.

Melt 15 oz. of the remaining butter in large saucepan on medium-low heat. Add combined flour, salt and pepper; cook 2 to 3 min. or until thickened, stirring constantly. Gradually stir in milk; cook just until mixture comes to boil and thickens slightly, stirring frequently. Stir in cheeses; cook until melted. Remove from heat. Stir in onions and about 1-1/4 qt. of the bacon.

Drain pasta; place in large bowl. Add sauce; toss to coat. Spoon about 1-1/2 cups into each of 50 (5-inch) greased crocks; place in sheet pan.

Melt remaining butter; mix with cracker crumbs and herbs. Top each crock with 3 Tbsp. of the cracker mixture.

Bake in 300ºF-convection oven 10 min. or until lightly browned and bubbly. Top each with about 1 Tbsp. of the remaining bacon.