Preheat and prep: Preheat oven to 350°F (175°C). Spray a 10x15-inch jelly roll pan, line with parchment, and spray parchment lightly.
Beat egg whites: In a large bowl, beat egg whites, lemon juice, and salt on medium-high until foamy. Gradually add sugar and beat until soft peaks form.
Fold in flour: Sift cake flour over the egg whites. Gently fold with a rubber spatula until just combined. Do not overmix.
Divide and color: Divide batter evenly into three bowls. Add a different gel food color to each bowl and fold gently until uniform.
Swirl and spread: Drop spoonful of each colored batter randomly into the prepared pan. Use a knife or skewer to gently swirl colors together. Spread into an even layer.
Bake: Bake for 12 minutes, until cake springs back when touched.
First roll: Immediately flip cake onto a clean towel or parchment dusted with powdered sugar. Peel off baked parchment. Starting at a short end, roll cake up with the towel inside. Cool completely on a wire rack.
Make filling: In a medium bowl, beat cream cheese, heavy cream, sugar, and vanilla until medium-stiff peaks form. Fold in crushed candies.
Unroll and fill: Gently unroll cooled cake. Spread filling evenly over cake, leaving a small border around edges.
Re-roll: Roll cake back up tightly, without the towel inside. Wrap in plastic and chill for at least 30 minutes.
Decorate and serve: Dust with powdered sugar and top with extra crushed candies before slicing and serving.
