Preheat your oven to 300°F (150°C). Line two baking sheets with parchment paper.

In a double boiler, combine fresh egg whites and granulated sugar. Whisk for about 1-1.5 minutes until frothy.

Transfer the mixture to a stand mixer and whisk on high until stiff peaks form, about 2-3 minutes.

Sift together almond flour, cocoa powder, and powdered sugar into a bowl, then gently fold into the meringue.

Transfer the macaron batter into a pastry bag and pipe quarter-sized circles onto the baking sheets.

Bake for approximately 13 minutes, rotating trays halfway through, until crisp outside and soft inside.

While baking, mix peanut butter and butter until smooth. Add sifted powdered sugar, vanilla extract, and salt, mixing until creamy.

Once shells are cool, pipe the filling onto half of the shells and sandwich with the remaining shells.