Preheat The Oven'S Broiler, And Set The Oven Rack About 6 Inches From The Heat Source. Whisk Together Sour Cream, Yellow Mustard, And Honey In A Small Bowl. Refrigerate Until Ready To Use. Cut Each Chicken Breast Into 2 Equal Pieces. Sprinkle Both Sides Of Chicken Breasts With Onion Powder. Place A Large Skillet Over Medium-High Heat; Coat With Non-Stick Cooking Spray. Cook Chicken Breasts Until Browned On Bottom. Turn Chicken, And Top With A Slice Of Ham And A Slice Of Cheese. Continue To Cook Until The Chicken Is Cooked Though And The Cheese Is Melted. Place Rolls, Cut Side Up, Under Broiler. Toast Until Lightly Browned. Top Each Chicken Cordon Bleu Burger With A Tablespoon Of Honey-Mustard Sauce, And Serve On Toasted Onion Rolls.