In a shallow, heat-resistant, non-metallic baking dish, place ham slices. Top each ham slice with cheese.
Place cooked broccoli spears on top of each cheese-topped-ham slice. Set aside.
In a medium-sized, heat-resistant, non-metallic bowl, melt the one tablespoon butter, uncovered, in Microwave Oven 30 seconds.
Blend in the flour, salt, horseradish, mustard, Worcestershire sauce and onion. Set aside.
Combine beaten egg yolk and pineapple juice.
Add pineapple juice mixture to butter mixture. Blend well.
Stir in milk.
Heat, uncovered, in Microwave Oven 5 minutes, stirring every minute until sauce is thick and bubbling.
Spoon about 1 tablespoon of sauce over broccoli.
Roll ham and cheese around broccoli and secure with wooden toothpicks.
Heat, covered, in Microwave Oven for 8 minutes.
Spoon remaining sauce over ham rolls. Top with pineapple slices.
Heat, uncovered, in Microwave Oven 2 to 3 minutes or until sauce is bubbly.