Step 1: Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish with butter to prevent sticking.

Step 2: In a large mixing bowl, use an electric mixer to cream together the room-temperature butter, granulated sugar, brown sugar, and 1/2 cup of the peanut butter until the mixture is light and fluffy.

Step 3: Beat in the egg and vanilla extract until the mixture is smooth and well combined.

Step 4: In a separate bowl, sift together the all-purpose flour, baking soda, and salt. Stir in the quick-cooking oatmeal to mix thoroughly.

Step 5: Gradually add the dry ingredients to the wet ingredients, mixing until everything is just combined. Avoid overmixing to keep the texture of the bars tender.

Step 6: Spread the batter evenly into the prepared baking dish. Sprinkle the butterscotch chips over the top.

Step 7: Bake in the preheated oven for 20-25 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean.

Step 8: While the bars are baking, prepare the glaze by whisking together the powdered sugar, milk, and the remaining 1/4 cup of peanut butter until smooth.

Step 9: Once the bars are done, remove from the oven and immediately pour the glaze over the warm bars, spreading it out to cover the surface.

Step 10: Allow the bars to cool completely in the pan on a wire rack before slicing into squares to serve.

Variation

For a nut-free version, substitute the peanut butter with a seed butter like sunflower butter, and replace the butterscotch chips with chocolate chips or a safe alternative that meets dietary needs.