This is your new favorite one-pan dessert! A rich, dense, and chewy peanut butter blondie is filled with chocolate chips and finished with a creamy, striking swirl of melted chocolate and peanut butter on top. This flavor combo is impossible to resist!
Preheat the oven to 350 degrees F. Spray 10" x 15" bar pan with cooking spray.
In a large microwave safe bowl, add the butter and coconut oil. Melt in microwave for 30 seconds and stir well. If not yet fully melted, continue to microwave in 30 second intervals until completely melted. Allow to cool.
To the melted oil and butter, add the brown sugar and whisk until combined. Then add in the peanut butter, eggs, and vanilla and continue to whisk until fully combined.
To a sifter, add the flour, baking powder and salt. Sift into the peanut butter mixture. Fold together with a rubber spatula until thoroughly combined. Then fold in the 6 ounces of chocolate chips.
Bake for 40 minutes (I used a stoneware bar pan, if you are using a regular metal pan, then start checking if they are done at 20-30 minutes), rotating the pan at the halfway point. Test if the blondies are done by inserting a toothpick in the center - if it comes out clean the bars should be done. If necessary, continue to bake in 5 minute increments until done.
While the bars are baking, add 6 ounces chocolate chips and 1 tablespoon coconut oil to a small microwave safe bowl, and microwave at 50% power in 30 seconds intervals, stirring each time, until the chocolate and oil are fully combined and melted. In another small microwave safe bowl, add the 1/2 cup peanut butter and 1 tablespoon coconut oil and microwave for 30-60 seconds until melted, stirring well. Set both bowls aside.
Place bars on a cooling rack. While the bars are still hot, dollop alternating spoonfuls of melted chocolate and peanut butter across the surface. Use a butter knife or skewer to create a beautiful marbled swirl, then cool completely.