Step 1

Preheat the oven to 375°F. Line the bottom of a 10x15x1 baking sheet with parchment paper. Lightly spray the baking sheet with nonstick cooking spray. Set it aside.

Step 2

In a small mixing bowl, whisk together the flour, baking powder, and salt. Set it aside.

Step 3

Using a stand mixer or a medium-sized mixing bowl and a handheld mixer on high speed, beat the egg whites and white vinegar to medium peaks.

Step 4

Continue mixing on high and slowly add the ¼ cup of granulated sugar. Continue beating the egg white mixture to the stiff peak stage. This could take between 5 to 7 minutes. Set egg yolk mixture aside.

Step 5

Using a stand mixer or a large mixing bowl and a handheld mixer on medium-high speed, beat the egg yolks until they reach a slightly pale yellow color, about 2 minutes.

Step 6

Add the ½ cup granulated sugar, milk, vanilla, and almond extract. Continue mixing for another 1½ to 2 minutes until well incorporated.

Step 7

Add half of the flour mixture, and mix just until combined. Add the remaining flour, and mix until completely incorporated.

Step 8

Fold in the egg white mixture a quarter at a time.

Step 9

Evenly sprinkle the red and green sprinkles onto the prepared baking sheet.

Step 10

Pour the cake batter on top of the sprinkles. Gently tap the baking sheet to release any bubbles.

Step 11

Bake for 10 to 12 minutes, until just golden.

Step 12

While the cake is baking, lay out a thin tea towel and dust it with ¼ cup of powdered sugar. You will also need a large cutting board for the dusted cake transfer.

Step 13

When the cake has finished baking, run the tip of a sharp knife along the edge of the baking sheet.

Step 14

Carefully flip the dusted tea towel on top of the baked cake, dusted side against the cake. You will need to leave a small “tail” of the tea towel on the short edge of the cake for rolling the cake up.

Step 15

Place a large cutting board on top of the tea towel. Remember, the baking sheet will still be very hot, so be sure to protect your hands.

Step 16

Quickly flip the baking sheet over, so it is now lying on top of the tea towel and cutting board.

Step 17

Carefully peel off the parchment paper.

Step 18

Lightly dust the top of the cake with powdered sugar.

Step 19

Flip the small tail of the tea towel over the short edge of the cake. Carefully begin rolling one end toward the other. Once rolled, transfer to a cooling rack to finish cooling completely.

Step 20

In a medium-sized mixing bowl and using a handheld mixer on medium-high speed, beat together the butter and shortening for 1 to 1½ minutes.

Step 21

Add the vanilla and almond extract. Continue mixing on medium-high until well incorporated.

Step 22

Lower the mixer speed to low. Add the powdered sugar ½ cup at a time, alternating with the heavy cream. Once all ingredients are added, increase the mixer speed to high and mix until completely combined and smooth.

Step 23

Once the cake is completely cooled, slowly unroll the cake.

Step 24

Using either a silicone spatula or an offset spatula, spread the filling. Be careful to avoid the edges of the cake.

Step 25

Evenly sprinkle the red and green sprinkles over the buttercream.

Step 26

Once filled, slowly and with even pressure, begin rolling the cake back up.

Step 27

Tightly wrap the rolled cake in plastic wrap to ensure the cake holds its shape. Chill in the refrigerator for 6 hours to overnight.

Step 28

Just before you are ready to serve the cake, using a microwave-safe bowl, combine the white baking chips and heavy cream.

Step 29

Heat in the microwave for 45 seconds, stir, and heat in 20-second intervals until the mixture is completely melted and smooth.

Step 30

Remove the cake roll from the plastic wrap and place it on top of a cooling rack with parchment paper underneath.

Step 31

Drizzle the melted chocolate mixture over the cake roll. Sprinkle the holiday sprinkles over the top of the chocolate.

Step 32

Transfer the cake roll to a serving plate. Slice ½-inch slices of the cake and serve.