peanut butter swirled brownies

Heat oven: To 350°F (175°C). Line an 8-inch square baking pan with parchment and coat the bottom and sides with nonstick cooking spray or butter. Make peanut butter batter: Whisk all ingredients in a bowl until smooth.Make brownie batter: In a medium heatproof bowl over gently simmering water, melt chocolate and butter together until only a couple unmelted bits remain. Off the heat, stir until smooth and fully melted. You can also do this in the microwave in 30-second bursts, stirring between each. Whisk in sugar, then eggs, one at a time, then vanilla and salt. Stir in flour with a spoon or flexible spatula.Assemble brownies: Spread a thin layer of brownie batter (about 1/3 of total batter, but no need to be exact) in bottom of prepared baking pan. Dollop peanut butter batter all over in big spoonfuls. Dollop remaining brownie batter in pan, aiming, if you can, between the peanut butter dollops. Use a butter knife to swirl the batters together in loose figure-8s. Sprinkle chips all over.Bake: For 30 to 35 minutes, or until a toothpick inserted into the center comes out batter-free.To keep: Brownies keep well at room temperature, in the fridge or freezer.