gel food coloringred, orange, yellow, green, blue, and purple
Powdered sugarfor dusting
¾cupsalted sweet cream buttersoftened
1teaspoonclear vanilla flavoring
Preheat the oven to 350°F. Line a 10x15x1-inch baking sheet (jelly roll pan) with parchment paper. Set it aside.
Add the flour, baking powder, and salt to a small mixing bowl. Whisk to combine.
Using either a stand mixer or a medium-sized mixing bowl and a handheld mixer on high speed, beat together the eggs, sugar, vegetable oil, vanilla, and almond extract for 5 to 6 minutes, until thickened and light yellow.
Gently fold in the flour mixture until combined.
Quickly and gently divide the batter between 6 bowls (about ⅔ cup each).
Add 1 color of the gel food color per bowl. Depending on how dark you want to tint the batter, we recommend 3 to 5 drops. Gently fold the gel into the cake batter.
Spoon the individual colors into 6 disposable piping bags or quart-size ziplock bags. Secure the tops of the bags.
Lightly spray the prepared baking sheet with nonstick spray, paying close attention to the edges.
Snip off a small corner of the bag. Starting at 1 corner of the prepared baking sheet, gently squeeze a small amount of the red batter. Be sure to keep the line as straight as possible. Next, gently squeeze a line of orange batter ¾ inch-1 inch wide. Next, the yellow, green, blue, and purple. Continue until the pan has been covered. Lightly tap the pan on the counter to remove any air bubbles in the cake batter. Bake for 8 minutes.
Remove the pan from the oven. Measure out a piece of parchment paper to roll the cake in. You will need to leave about a 2-inch overhang to begin the cake roll. Lightly dust the baked cake.
ELEVENTH STEP: Have a large cutting board or cooling rack ready to aid in the cake transfer.
While the cake is warm, lay the piece of parchment paper over the powdered sugar-dusted cake. Place the cutting board (or cooling rack) on top of the parchment. Carefully flip the cake over so that the cake is resting on the dusted piece of parchment and cutting board/cooling rack.
Remove the upside-down cake pan, and carefully peel off the parchment paper that the cake was baked on.
Fold the overhanging end of the parchment paper up onto the cake and then gently and patiently start rolling the shorter side of the cake towards the other short side. The parchment paper will be rolled up inside the cake. Once rolled, transfer to a cooling rack to finish cooling completely.
Using either a stand mixer or a medium-sized mixing bowl and a handheld mixer on medium-high speed, beat the softened butter for 1 to 1½ minutes until smooth.
Add the clear vanilla and the almond extract and continue mixing for another 30 seconds.
Lower the mixer speed to low, and beat in the powdered sugar 1 cup at a time. Alternate with the heavy cream. Increase the speed back up to medium-high and continue mixing for 1 more minute until smooth.
Once the cake has completely cooled, gently unroll the cake. Using either a silicone spatula or an offset spatula, spread the filling over the surface of the cake roll, avoiding the outer edges.
Tear off 2 sheets of plastic wrap to overlap the long edges and lightly spray with nonstick spray. This is for tightly wrapping the filled cake roll.
Slowly roll the cake back up as before. Transfer the cake roll to the prepared plastic wrap. Roll the finished cake roll up in the plastic wrap. Once finished wrapping, twist the ends tightly to seal the cake roll securely. Chill in the refrigerator for 6 hours. Remove just before serving to slice the cake into ten ½-inch slices.