In the bowl of a stand mixer with the whisk attachment, whip the heavy cream until stiff peaks, about 3½ minutes on high speed.

In a separate large bowl, combine the sweetened condensed milk and sifted cocoa powder. Fold the whipped cream into the chocolate mixture until no white streaks appear.

Gently fold in most of the halved peanut butter cups, saving a few for the top, for looks.

Using a 2 quart container, pour ⅓ of the chocolate mixture. Drizzle with the melted peanut butter. Pour another ⅓ of the chocolate mixture; drizzle with peanut butter. Pour the last ⅓ of the chocolate mixture. Drizzle with peanut butter, and swirl with a knife. Top with remaining halved peanut butter cups.

Freeze 6 hours or until firm; freezing overnight is good. Store in the freezer.