1. Line an 8x8 pan with foil or parchment paper and set aside.

2. In a medium saucepan, melt together butter, honey, Reese's spread and brown sugar. Bring to a boil, then simmer for 3 minutes, stirring constantly. Remove from heat and add in vanilla.

3. In a large bowl, combine oats, rice cereal and mini Reese's Pieces. Pour in Reese's spread mixture and stir until everything is completely coated.

4. Pour mixture into prepared pan and sprinkle additional Reese's Pieces on top, if desired. Using parchment paper, press mixture firmly and evenly into pan.

5. Cool in refrigerator for 30 minutes and then cut into bars.