I have been looking for this recipe for at least 20 years. I came across it on Pinterest! We used to love these bars. Our recipe used to have Caro Syrup in it, so I replaced the white sugar ingredient. The Caro syrup makes the bars gooier!
Ingredients
1 1/2 C Flour
1 1/4 tsp. Salt
1/2 tsp. Baking Soda
3/4 C Butter
3/4 C Caro Syrup
3/4 C Brown Sugar
1 1/2 tsp. Vanilla
1 1/2 C Creamy Peanut Butter (split)
2 Eggs
1 1/2 C Quick Oats
Frosting
1/2 C Butter (1 stick)
1/2 Bag Nestle Chocolate chips
1/4 Condensed Milk (or whatever I have in the fridge)
1 tsp. Vanilla
Instructions
Preheat oven to 350 degrees. In a small mixing bowl, mix together flour, baking soda and salt. In a large mixing bowl, cream together butter, sugar, Caro Syrup, 3/4 C peanut butter, eggs and vanilla until light and fluffy. Gradually add dry ingredients, just until incorporated. Then, stir in the oats. Spread onto a greased 11 x 15 Jelly Roll Pan (cookie sheet). Bake for 12-15 minutes, or until golden brown. Cool for 10 minutes.The frosting is a two-step process. First, whip the remaining 3/4 C Creamy Peanut Butter until it becomes lighter colored and fluffy. Carefully spread the whipped peanut butter over the pan cookie. Then, add butter to a small sauce pan and melt the butter. Add the milk and cocoa. Cook over medium heat, stirring constantly. Heat just until boiling. Remove from heat and add vanilla. Then, gradually add the powdered sugar. Stir until thickened. Pour over the peanut butter and gently spread over the cookie. Cool completely, and slice into bar cookies.
Kim's What's Up 
As a peanut butter fan, I’ve got to say, these sound phenomenal! At my children’s old school, they weren’t allowed to bring peanut butter-anything into class, so I guess I’d just have to keep it at home (and eat it by myself).
Do you use sweetened condensed milk for the frosting?
I have before, but not always