• Preheat the oven to 350°F.
• Line a 9x9-inch baking pan with parchment paper. Set aside.

Chocolate Brownie Batter

• Melt the butter in a medium mixing bowl using the microwave- should only take about 30 seconds or less.
• Stir in the sugar until well incorporated.
• Whisk in the eggs and vanilla until the mixture is smooth.
• Fold in the cocoa powder, flour, and salt, mixing just until combined. Set aside.

White Chocolate Brownie Batter

• Combine the white chocolate and butter in a separate medium mixing bowl. Microwave on 50% power in 30-second intervals, stirring inbetween each. It should only take about 30-40 seconds. Stir until smooth. Let cool slightly.
• Whisk in the sugar, eggs, and vanilla until smooth.
• Fold in the flour, and salt, mixing just until combined.
• Alternating between the two batters, add scoops of each into the prepared pan.
• Use a knife or skewer to gently swirl the batters together, leaving visible streaks of each.
• Bake for 35–40 minutes, or until the center is set and a toothpick inserted comes out with a few moist crumbs.
• Cool completely before slicing to ensure clean edges and defined swirls.