Vertical Layer Cake

1. Stage

Preheat oven to 350°. Line a half sheet pan and a quarter sheet pan with parchment paper and generously grease both with cooking spray. In a medium bowl sift together flour, cocoa powder, and salt. 

2. Stage

In a large bowl beat egg yolks until thick. Gradually add ¾ cup sugar in stages and beat until pale. Fold in 3 tablespoons crushed Oreos and flour mixture. 

3. Stage

In another large bowl beat egg whites until soft peaks form. Add remaining 3 tablespoons sugar a little at a time and continue to beat until stiff peaks form. Gently fold egg whites into batter in two batches.

4. Stage

Pour ⅔ the batter into prepared half sheet pan and the remaining ⅓ batter into prepared quartered sheet pan, spreading each into an even layer. Bake until tops spring back when lightly pressed, 14 to 16 minutes. 

5. Stage

Dust two clean kitchen towels with powdered sugar and invert warm cakes onto towels. Peel off parchment paper. Starting at the short end, use the towel to tightly roll each cake into a log. Let cool completely. 

6. Stage

Make filling: In a small microwave-safe bowl, pour in water and sprinkle gelatin evenly on top. Let bloom for 5 minutes, then microwave for 10 seconds until fully liquid—do not overheat! Strain out unmelted gelatin, if necessary. 

7. Stage

In a large bowl using a hand mixer, beat together heavy cream, powdered sugar, pure vanilla extract, and salt, until medium peaks form. Slowly stream in melted gelatin and continue beating until stiff peaks form. Refrigerate for at least 30 minutes, until ready to use. 

8. Stage

When cake is cool, unroll gently and slowly. Using a bench scraper, divide the larger cake into 3 long strips and divide the smaller cake into 2 long strips, trimming excess off sides so that each strip measures about 3 ⅔” wide. 

9. Stage

Spread half the filling evenly over the 5 strips of cake. Roll one strip back into a spiral, connecting it with the next strip, until all strips are connected into one single spiral cake. Turn cake on its side and transfer to a platter, so that the spiral swirl is visible from the top. Wrap tightly in plastic wrap and refrigerate until well chilled, at least 1 hour, up to overnight. 

10. Stage

Once rolled cake is fully chilled, use remaining filling to frost cake evenly. Chill until ready to decorate.

11. Stage

In a medium microwave-safe bowl, microwave chocolate and oil in 20 second increments until fully melted, stirring well after each increment. Drizzle on chilled cake, letting some chocolate drip off the sides, then top with Oreos.