Peanut Butter Swirl Brownies

Steps

1. Heat the oven to 350°F (175°C). Brush an 8-inch square pan with the canola oil and line it with parchment, leaving an overhang.
2. Make the peanut butter swirl first: in a small bowl, stir the peanut butter with the powdered sugar until smooth and glossy. Warm it for 10 seconds in the microwave if stiff, then set aside.
3. In a large bowl, whisk the melted butter with the granulated sugar and the brown sugar until combined.
4. Whisk in the eggs one at a time, then the vanilla, until the batter is thick and shiny.
5. Sift the unsweetened cocoa powder over the bowl, add the flour and salt, and fold just until no dry streaks remain.
6. Spread about two-thirds of the brownie batter in the pan. Drop half of the peanut butter swirl over it in spoonfuls.
7. Spoon the remaining one-third of the brownie batter between the peanut butter, then dollop the remaining half of the peanut butter swirl on top.
8. Drag a butter knife through the pan in loops to marble the peanut butter and batter without overmixing.
9. Bake 26 to 30 minutes, until the edges are set and a toothpick in the center comes out clean or with a few moist crumbs, not wet batter.
10. Cool in the pan on a rack for at least 1 hour, then lift out with the parchment and cut into 12 bars.