14 tablespoons (1 3/4 sticks) butter, softened
Preheat oven to 350 degrees F. Line a 9 x 13 baking pan with foil and set aside.
In the bowl of an electric mixer, beat butter, brown sugar and baking soda together until creamy. Add in eggs and 2 teaspoons of vanilla until combined.
With the mixer on low, add in the flour and mix until completely incorporated, scarping down sides of bowl as you go. Add in the rolled oats (you may need to use a little elbow grease to mix them in). Set dough aside.
For the filling, combine peanut butter, chocolate and sweetened
condensed milk in a microwave safe bowl. Heat mixture in microwave,
stirring every 20 seconds, until chocolate is melted. Stir unril
smooth, then add peanuts and 2 teaspoons vanilla.
Bake 22-25 minutes, until top is lightly browned. The chocolate may still look moist. Allow bars to cool completely on a wire rack.