In a large mixing bowl, add rice squares, toasted o's and mini marshmallows. Stir to mix well.
Melt white candy bark in a saucepan over low heat stirring constantly. Remove from heat and stir into cereal. Mix well to coat and combine. Add candy hearts and pearls and mix well.
Pour mix onto prepared pan and spread out. Let set to harden.
When harden, break apart with your hands or gently "drop" the baking sheet onto the counter top to break apart into smaller pieces.