In large bowl, combine marshmallows and butter. Microwave for 2 minutes and stir.

Add Fruity Pebbles to melted marshmallow mix and press into the bottom of a spring form pan. Set in fridge until ready to use.

In large bowl, blend the cream cheese and lemon juice until combined.

Add heavy cream, vanilla, and sugar and mix until smooth and silky.

Pour the cream cheese mixture on top of the Fruity Pebble crust, using a spatula to create a smooth top.

Chill for 3 hours.