1. In large saucepan, melt butter over medium-high heat. Stir in brown sugar, cream, and cocoa; boil 1 minute.
2. Remove saucepan from heat, add peanut butter and vanilla, and stir until smooth. Stir in oats and peanuts.
3. Drop heaping tablespoonfuls of the batter onto wax paper–lined baking sheets, spacing 1 inch apart, and let cool until set, about 20 minutes.
4. Storage suggestion: Keep the cookies at room temperature, between sheets of wax paper in an airtight container, for up to 3 days.