In a small bowl, mash together butter, mustard, onion & Worcestershire sauce until combined & thick. Unroll bread, remove towel & top with ham slices; spread filling mixture over ham & sprinkle with shredded Swiss cheese. Reroll bread & place, seam side down on lined jelly roll pan. Sprinkle with remaining cheddar cheese & bake until cheese is melted, about 5-6 minutes.