01 -
Preheat the oven to 350° F. Line a 9x13 inch baking dish or 13x18 inch half sheet pan with parchment paper.
02 -
In a large mixing bowl, beat together the butter, brown sugar, 1 cup of peanut butter, and vanilla until combined. Beat in the eggs. Add the flour, oats, baking soda, and salt.
03 -
Press or spread the dough out into the prepared dish. Bake for 18-22 minutes, until just set in the center. Remove from the oven and dollop 1 ½ cups of peanut butter over the bars, lightly spreading it in an even layer. Let cool completely, chilling in the fridge to speed this up if desired.
04 -
In a bowl, whisk together the powdered sugar, cocoa powder, vanilla, and 3 tablespoons of water until smooth. Stir in the melted chocolate. If the icing is too thick, thin with 1-2 additional tablespoons of water.
05 -
Spread the icing over the cooled bars. Let set for about 1 hour, then slice and serve.