Makes 12 cups.
Truffle Layer & Topping
Peanut Butter Filling
Cook's Note:If using pure peanut butter, the peanut butter cups will be slightly softer at room temperature than if using conventional peanut butter, but they work equally well.
Preheat the oven to 350ºF (180ºC). Line a muffin tin with paper liners.
Sift the flour, cocoa powder and sugar into a large mixing bowl. Add the butter and use a pastry cutter or 2 butter knives to cut in the butter until no large pieces are visible (but the mixture will be coarse and not come together). Divide the mixture between the muffin tins and use a flat-bottomed water glass dipped in flour to press down the base (don’t worry if it looks rough, the base will level out when baked). Bake this for 12 minutes and then cool completely on a rack.
For the truffle layer, place the chocolate, peanut butter and corn syrup in a metal bowl over a pot of gently simmering water, stirring until melted. Measure out just under half of this (it makes about 1 cup/250 mL in total) and pour a little into each muffin cup, swirling the tins to coat the bases. Set aside the rest of the truffle mixture for the topping.
For the peanut butter filling, place the white chocolate and cream in a small bowl place over a pot of barely simmering water stirring gently until smooth. Set aside.
Beat the peanut butter and butter by hand until smooth and stir in the melted white chocolate (still warm is OK). Add the icing sugar and salt and stir until smooth. Place this in a piping bag fitted with a plain tip and pipe the filling into each cup (the truffle filling below does not need to be set up). Spread the filling to level it, if needed.
To top the cups, pour the remaining truffle mixture over each cup (if it has set up, it can be re-melted in a bowl over simmering water) and swirl the tins to ensure the topping covers the peanut butter layer. Sprinkle the top of each cup with a little chopped peanuts and then chill to set. Once set, the cups can be stored at room temperature (see Cook’s Note).