In a medium bowl or stand mixer, whip heavy cream until stiff peaks form, around 2-3 minutes.
In a large bowl, blend peanut butter and powdered sugar together until mixed thoroughly. It'll be difficult to incorporate at first but then you'll get it to relax. It should be completely smooth.
Using a large rubber spatula, gently spoon the whipped cream into the peanut butter bowl without mixing it. Once all the whipped cream is in the pb bowl, use the narrow, long edge of the spatula to slice through the center of the peanut butter and whipping cream, turning over the spatula while turning the bowl. You don't want to stir the whipped cream or you'll deflate the cream. For more info, see this video on how to fold ingredients for baking.
The entire folding process should take around 2 minutes or so and the peanut butter and whipped cream should be completely folded together.
Spoon into serving bowls or use to layer a cake.
Make ahead tip: can also be refrigerated until needed but let it stand at room temperature for about 15 minutes
For a crowd:
Use the recipe as is and serve in small shot glasses on a tray for a big party.
Pipe on to a ginger snap cookie for a brunch or cocktail party accessorized with some chopped chocolate.
For a few: Halve the recipe and serve 4-6 at the end of a great meal.