Preheat oven 350
Line a 9x13 pan with nonstick foil.
IN a sauce pan, melt butter and add chips.
Once smooth, turn off heat but keep pan on the burner.
In a bowl, whisk eggs.
Add sugar and salt.
Slowly whisk in the chocolate mixture.
Add vanilla.
Sift in flour and cocoa.
Stir in pb cups. Spread in pan and bake about 25 minutes.
Let cool 15 minutes and place in fridge for 7 hours or overnight!