Preheat oven to 350.
Cut Hawaiian rolls in half.
Mix 3 tbsp mayo and 1 1/2 tbsp dijon mustard.
Spread sauce on bottom of rolls.
Layer ham and Muenster cheese.
Combine 1/2 cup melted butter, 2 tbsp poppy seeds, 1/2 tbsp onion powder and 1/2 tsp Worcestershire sauce.
Pour liquid over top of sandwiches.
Cover with foil.
Bake for 10 minutes.
Remove foil.
Bake for 10 minutes.