Preheat your oven to 375°F (190°C). Line a 15x10 inch jelly roll pan with parchment paper, leaving an overhang on the short sides. Grease the parchment paper lightly.

In a large bowl, whisk together the all-purpose flour, cornstarch, baking powder, and salt. Sift this mixture twice to ensure it's lump-free and aerated. Set aside.

In a clean, dry bowl of a stand mixer with the whisk attachment (or using a hand mixer), beat the egg whites on medium-high speed until soft peaks form. Gradually add 1/4 cup of the granulated sugar, continuing to beat until stiff, glossy peaks form. Transfer the meringue to a separate bowl and set aside.

In the same mixer bowl (no need to clean), beat the egg yolks with the remaining 1/4 cup granulated sugar on high speed until thick, pale yellow, and tripled in volume (about 3-5 minutes). Beat in the vanilla extract.

Gently fold half of the dry ingredient mixture into the egg yolk mixture using a rubber spatula until just combined. Then, gently fold in half of the meringue. Repeat with the remaining dry ingredients and meringue until no streaks remain, being careful not to deflate the batter.

Pour the batter evenly into the prepared jelly roll pan and spread it to the edges. Bake for 12-15 minutes, or until the cake springs back when lightly touched and the edges are lightly golden.

While the cake is baking, lay a clean kitchen towel on your counter and dust it generously with powdered sugar.

Immediately after removing the cake from the oven, invert it onto the sugared towel. Carefully peel off the parchment paper. Trim any crisp edges of the cake with a sharp knife if desired. Starting from one short end, carefully roll the warm cake and towel together. Place the rolled cake, seam-side down, on a wire rack and let it cool completely for at least 30-45 minutes.

In a medium bowl, beat the softened cream cheese and unsalted butter with an electric mixer until smooth and creamy.

Gradually add the sifted powdered sugar, beating until fully incorporated and light and fluffy. Beat in the peppermint extract. Finally, add the heavy cream and beat on medium-high speed until the mixture is light, fluffy, and holds its shape.

Once the cake is completely cool, carefully unroll it. Spread the peppermint cream filling evenly over the entire surface of the cake, leaving about a 1/2-inch border along the edges.

Starting from the same short end you rolled it from initially, carefully re-roll the cake, without the towel, as tightly as possible. Place the roll cake seam-side down on a serving platter. Chill in the refrigerator for at least 30 minutes to firm up.

While the cake chills, prepare the ganache. Place the finely chopped white chocolate in a heatproof bowl. In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer (do not boil). Pour the hot cream over the white chocolate and let it sit for 5 minutes.

Whisk the mixture until smooth and glossy. If lumps remain, microwave in 10-second intervals, stirring after each, until smooth. Let the ganache cool slightly at room temperature, stirring occasionally, until it reaches a pourable but thickened consistency (about 10-15 minutes).

Pour the ganache evenly over the chilled roll cake, allowing it to drip down the sides. Spread with an offset spatula if needed.

Immediately sprinkle the crushed candy canes over the top and sides of the ganache before it sets.

Refrigerate the Christmas Peppermint Roll Cake for at least 1 hour, or until the ganache is fully set and the cake is firm enough to slice cleanly.

Slice with a sharp knife (dipped in hot water and wiped clean between slices for best results) and serve cold. Enjoy your festive Christmas Peppermint Roll Cake!