Preheat oven to 325°F. Line an 8″ square baking pan with a parchment sling – cut one piece of parchment 8″ wide and about 14″ long so it lines the bottom exactly and extends over two of the sides so you can lift out the shortbread easily.
Melt butter and cool slightly.
Process powdered sugar, flour, almond flour and salt in the food processor until mixed well. Pour in melted butter and vanilla extract and pulse until a dough has formed.
Press the dough into the prepared pan – try to make it flat. Using a bench scraper or other straight edge, press the dough around the edges of the pan to even them out. Cut the dough down the middle of the pan so you have two 4″ halves. Now cut the dough perpendicular to that cut into 1″ strips. You will have sixteen 1″ bars.
Bake for about 1 hour 15 minutes, or until the shortbread is dark golden brown.
Sprinkle liberally with granulated sugar and let cool completely.
Lift shortbread out of pan and cut again following the cuts you made before. Be appreciated.
Preheat oven to 200°F. Stir peanut butter and salt together in a large, heatproof bowl. Place bowl in preheated oven to keep warm.
Combine vanilla and baking soda in a small bowl and keep handy next to the stove.
Combine sugar, corn syrup and water in a medium heavy-bottomed saucepan and bring to a simmer over medium heat. Once sugar has dissolved, attach a candy thermometer and cook until the syrup reaches 285°F.
Remove from heat and stir in baking soda and vanilla – the mixture will foam.
Carefully take peanut butter out of oven and fold in foaming syrup – fold together until the mixture is somewhat combined but there are still streaks of peanut butter throughout. The mixture will become quite stiff.
Working quickly while the mixture is still warm, divide among your silicon molds. Any molds will work, but I like these to be about 3/4″ to 1″ thick, so I don’t fill my molds all the way to the top. Any extra can be molded on parchment paper. The cooled bars don’t cut well, but you can break them up into shards which are just as tasty.
Let the butterfingers cool and harden for a couple hours or overnight. Remove from molds and dip in chocolate. Crispity crunchity.