Heat covered 4-quart saucepan of salted water to boiling on high. Add pasta and cook as label directs.
Meanwhile, preheat broiler. In 3-quart saucepan, cook pancetta on medium 5 minutes or until browned; with slotted spoon, transfer pancetta to paper towels to drain.
Add enough oil to drippings in pan to equal 1 tablespoon; whisk in flour and cook 30 seconds, whisking constantly. Gradually whisk in milk and heat to boiling on medium-high, stirring frequently. Boil 1 minute, stirring. Remove saucepan from heat; stir in Fontina cheese, 1/4 cup Romano cheese, and 1/4 teaspoon freshly ground pepper until cheese melts. In cup, combine remaining Romano with panko.
Drain pasta well. Stir pasta and pancetta into cheese mixture until evenly coated. Spoon mixture into 4-cup shallow gratin dish or 9-inch pie plate. Sprinkle with panko mixture.
Place dish on rack in bottom third of oven and broil 3 to 6 minutes or until browned.