1-First, preheat your oven to 325°F/163°C and line a 9″x13″ baking sheet with parchment paper. This preparation helps prevent sticking and ensures even baking. Next, whisk together 15 ml avocado oil, 60 ml whole milk, part of the 20 g granulated sugar, and ¼ teaspoon vanilla extract in a bowl.

2-Sift 40 g all-purpose flour and 10 g cornstarch into the mixture for a smooth batter. In a separate bowl, beat 140 ml egg whites until foamy, then add ¼ teaspoon cream of tartar and gradually mix in 35 g granulated sugar until soft peaks form. Gently fold the egg whites into the batter in thirds to keep it airy.

3-Pour the batter into the pan, smooth the top, and drop the pan from about a foot high to release air bubbles. Bake for 15-16 minutes until the cake is springy. After baking, drop the pan again and cool on a rack for 10-15 minutes. For the filling, whisk 125 ml cold heavy whipping cream, ¼ teaspoon vanilla extract, and 15 g powdered sugar in a chilled bowl until light and airy.

4-Assemble by peeling the parchment from the cake, spreading the whipped cream evenly, and rolling it up carefully. Wrap in parchment and plastic wrap, then refrigerate for at least 4 hours. Finally, trim the edges with a serrated knife, garnish if desired, and slice to serve. Prep time is about 30 minutes, with total time around 4 hours 45 minutes.