Crock pot Hawaiian roll ham sandwiches are the warm buttery mustard ham sandwich recipe made with onions, poppy seeds, and Swiss cheese without needing to bake them with the same results.
Turn the casserole crock pot on high and put a tablespoon of butter in the crock pot melt.
Melt the remaining eight tablespoons of butter in a small skillet. Once butter is melted, add onions to the pan.
When onions begin to become translucent, add mustard, Worcestershire sauce, and poppy seeds into onions and butter. Simmer for two to three minutes.
Remove rolls from the package, keeping them all connected and cut the rolls in half lengthwise. Place the bottoms in the melted butter in the bottom of the casserole crock pot.
Spread 1/2 of the butter and onion mixture across rolls bottoms followed by the ham and then the cheese. Add half of the remaining sauce to the top of the cheese.
Top with the tops of the roll and spread the remaining butter and onion mixture over the top of the rolls. Cover the crock pot.
Slow cook on high for an hour or low for two hours or until hot in the melted and cheese is melted.