In a medium bowl, beat sugar, peanut butter, salt, and vanilla with an electric mixer until well incorporated.
Place the peanut butter mixture between two pieces of parchment paper. Roll with a rolling pin to ¼-inch thickness. Using a 1-inch round cookie cutter, cut round pieces of peanut butter mixture and set aside.
Melt chocolate wafers over a double boiler, then pour half of the chocolate into a pastry bag. Keep melted chocolate over hot water to maintain the temperature.
Line mini muffin pans with paper liners. Add 1 tablespoon of chocolate into each of the liners. Tap the pan to ensure that the chocolate is level. Then place in the freezer for 5 minutes until the chocolate sets. Remove pan from freezer and place cutouts of the peanut butter mixture into each cup. Pour remaining chocolate on top of the peanut butter layer to cover all the filling. Tap the pan to ensure that the chocolate is level.
Decorate with cashews, almonds, and salt flakes. To make a pattern with peanut butter, heat two tablespoons of peanut butter in the microwave for 30 seconds. Pour a few dots of peanut butter on top of the chocolate and swirl with a toothpick.
Allow the chocolate to set at room temperature for about 2 hours. Enjoy!