Peanut Butter Swirl Brownies for Two are an easy, rich and chocolatey dessert perfect for peanut butter lovers.
Preheat your oven to 350°F. Grease a 9x5-inch loaf pan and line with parchment paper.
In a medium bowl, combine sugar, cooled butter (if it's too hot, it will scramble your egg), egg, and vanilla. Whisk until well-combined.
To the same bowl, add flour, cocoa powder, baking powder, and salt. Stir until just combined.
Transfer mixture to your prepared pan and use a knife to spread the batter so that it mostly covers the bottom of the pan.
In a small bowl, whisk together peanut butter, melted butter, powdered sugar, vanilla, and salt until well-mixed. Drop the peanut butter mixture by the spoonful over the brownie batter.
Use a knife to swirl in the peanut butter by drawing 3 horizontal lines down the long side and then making an "S" shape across them.
Bake for 22 to 25 minutes, until a toothpick inserted into a non-peanut butter section near the middle comes out with just a few crumbs.