Melt butter and peanut butter in a large saucepan over low heat. Stir in chips till melted.

Cool until you can hold your hand on bottom of pot. To speed process, stir while holding bottom of pan in cold water.

Add marshmallows and stir until all are coated.

Pack down into a 9 x 9 inch pan that has been lined with wax paper.

Refrigerate then cut into squares. Makes 36 squares. Freezes well.