Begin by soaking the gelatin sheets in cold water for about 5 minutes, or until they become soft. After soaking, gently squeeze out the excess water and dissolve the gelatin in 100ml of warm water. Set it aside to cool.
In a food processor, crush the chocolate graham crackers into fine crumbs. If you don’t have a food processor, placing them in a zip-lock bag and using a rolling pin works just as well.
In a mixing bowl, combine the softened cream cheese with the cooled gelatin mixture. Use an electric mixer on low speed to blend until smooth and creamy.
In a separate bowl, beat the egg whites until they form soft peaks. Gradually add the caster sugar while continuing to beat until stiff peaks form.
Gently fold the cream cheese mixture into the whipped egg whites using a spatula. Be careful not to deflate the egg whites.
Divide the mixture into two equal parts. To one part, add the cocoa powder and mix until fully incorporated.
In the prepared springform pan, alternate scoops of the plain and chocolate mixtures, creating a striped effect.
Cover the pan with plastic wrap and place it in the refrigerator for at least 4 hours, or until set.
Once set, carefully release the sides of the springform pan. Slice the cake to reveal the stunning zebra pattern and serve chilled.