Of note I can't fairly count "This Is Halloween" because it's purely from a movie musical with no real stage equivalent.

5: "Omigod You Guys" from Legally Blonde

4: "Belle" from Beauty And The Beast (I don't count the prologue.)

3: "Willkkommen" from Cabaret

2: "In The Heights" from In The Heights

1: "Bikini Bottom Day" from Spongebob Squarepants