Preheat oven to 325F. Line an 8x8 square baking pan with parchment paper and set aside.

Separate eggs and place whites in a medium bowl. Place yolks in a separate large bowl and set aside. With a handheld electric mixer, beat egg whites on high speed until stiff peaks form, about 3 minutes. Set egg whites aside.

Meanwhile, whisk egg yolks, sugar, orange juice, lemon juice, both zests, butter, milk, and vanilla until smooth. Gradually whisk in flour and then very gently fold in whipped egg whites until batter is just combined. (there may still be a few streaks)

Spread batter into prepared pan. Bake magic cake at 325F 35-40 minutes or until top is a light golden brown and just slightly firm to the touch. Cool cake completely in pan on a wire cooling rack.

Make the berry sauce: In a small saucepan combine all sauce ingredients and bring to a simmer over medium-high heat. Reduce heat to medium-low and simmer 10 minutes until sauce is reduced and slightly thickened. Keep sauce warm.

Once cake has cooled, use the edges of parchment paper to remove from pan. Carefully cut cake into 12 bars. Serve magic cake bars with warm berry sauce and powdered sugar dusted on top. Enjoy!