In a large mixing bowl stir together softened butter, cream cheese, egg, and fudge packet (from brownie mix) until combined. Add brownie mix and stir until just combined.
Scoop 24 portions of dough and put them on a tray or plate that fits in the refrigerator. Chill for about 30 minutes or until the dough is still enough to be shaped into neat balls.
Meanwhile, beat together peanut butter, powdered sugar, and vanilla; stir until smooth dough forms. Form peanut butter dough into 24 equal balls and put them in the freezer for 30 minutes.
Preheat oven to 350°F. Line 2 baking sheets with parchment paper.
Once both doughs are chilled, shape the brownie dough into neat balls and the peanut butter dough into neat balls. Arrange brownie dough about 2 ½ inches apart on baking sheet. Press a ball of peanut butter dough into the center and press down slightly.
Bake cookies 10–12 minutes or until edges are crisp, then cool on baking sheet 2–3 minutes before transferring to cooling rack to cool completely.
Pour cream in a 2 cup liquid measure (or small bowl) and heat for 30 seconds until hot. Add chocolate morsels; let sit 2 minutes to melt. Stir chocolate mixture until smooth and combined. Spread about 1 tablespoon chocolate mixture over each cookie, then sprinkle with chopped peanuts, if desired. Serve.