Peanut butter and butterscotch is such an awesome flavor combination. The butterscotch flavor is prominent and really shines. Sweet with a bit of saltiness, caramely, and buttery. If you’re a fan of butterscotch, you’ll love these. The bars are soft with slight chewiness and texture from the oats. The peanut butter frosting is thick, luscious, rich, creamy, and you’ll be tempted to eat the whole bowl before it even makes it onto the bars. Make the frosting while the bars bake and add it right as the bars emerge from the oven. The bars taste much more complicated than the simple, everyday ingredients used.
Preheat oven to 350F. Line an 8-inch square pan with aluminum foil and spray with cooking spray; set aside.
Bars – To the bowl of stand mixer fitted with the paddle attachment (or large mixing bowl and electric mixer), add the peanut butter, butter, sugars, and beat on medium-high speed to cream, about 3 minutes.
Stop and scrape down the sides of the bowl and add the egg, vanilla, and beat on medium-high speed until mixture is light and fluffy, about 3 minutes.
Stop and scrape down the sides of the bowl and add the flour, oats, optional salt, and beat on low speed until just combined, about 1 minute; don’t overmix.
Turn batter out into prepared pan, smoothing the top lightly with a spatula.
Evenly sprinkle with butterscotch chips.
Bake for about 25 minutes, or until edges are slightly firm and the center has just set. It’s a little tricky to tell if the bars are done because the surface is covered in semi-melted butterscotch chips, but a toothpick inserted in the center (if you can find a bare patch to test) should come out clean or with a few moist crumbs, but no batter. While bars bake, make the frosting.
Frosting – To the bowl of stand mixer fitted with the paddle attachment (or large mixing bowl and electric mixer), add the peanut butter, confectioners’ sugar, cream, and beat on medium-high speed until smooth, satiny, and creamy, about 3 minutes. Stop to scrape down the sides of the bowl, cover bowl with plastic wrap; set aside.
As soon as you pull bars from the oven, add the frosting (don’t wait for them to cool). Smooth the top lightly with a spatula or knife, and allow bars to cool completely in pan before slicing and serving. Bars will keep airtight at room temperature for up to 5 days.