Trim away the muffin bottoms, reserving for another use. Place the muffin tops on a baking sheet or serving tray.
Combine the cream cheese, peanut butter and confectioners' sugar in a stand mixer. Beat until smooth. Add some milk or cream if needed to thin to a spreading consistency. Spread the cream cheese mixture on the flat side of half of the muffin tops. Sandwich together with the remaining muffin tops. Serve right away.