Instructions:
1. Prepare your pans: Line a 9-inch round cake pan with parchment and spray the parchment with nonstick cooking spray. Spray a 12×18-inch rimmed baking sheet with nonstick cooking spray. Line it with parchment, spray the parchment, and dust it with a light layer of flour. Don’t skip this step or you won’t be able to roll the cake properly!
2. Preheat the oven to 325 F.
3. In a large bowl, sift or whisk together the cake flour, part of the granulated sugar (¾ cup or 5.25 oz), the baking powder, and salt.
4. In a separate small bowl, whisk together the oil, water, yolks, and vanilla extract.
5. Place the egg whites in the bowl of a large stand mixer fitted with the whisk attachment. Begin to whip them on medium speed. When the whites are frothy, add the cream of tartar and continue whipping.
6. Once they start to hold soft peaks, slowly add the remaining ¼ cup sugar, a spoonful or two at a time, until it’s all added. Beat the whites on medium-high speed until they’re glossy and hold firm peaks.
7. Add the yolk mixture to the dry ingredients, and stir them together with a spatula until smooth.
8. Gently fold a third of the beaten egg whites into the cake batter, trying not to over-mix and deflate the whites. Add the rest of the whites in two batches, stirring delicately.
9. Scoop 1 ½ cups of batter into the 9-inch round pan, and spread it into an even layer. Pour the rest of the cake batter into the sheet pan and gently smooth it into an even layer.
10. Bake the cakes at 325 F for 14-16 minutes, until they are a light golden brown and the cake springs back when lightly pressed. The two cakes might be done at different times, so watch them both carefully. Cool the cakes on a wire rack until they are at room temperature.
11. Once cool, spread the strawberry jam in a thin layer on top of the entire surface of the sheet cake.
12. Beginning at the long end nearest to you, start rolling the cake into a spiral, peeling the parchment off the back as you roll. Once it is a tight spiral, wrap cling wrap around the roll and refrigerate it for at least 2 hours. This chilling time will make the cake much easier to cut and will give you cleaner slices. The cake can be refrigerated overnight if desired.
13. To assemble this recipe, you’ll need a 3 or 4 quart round bowl. The exact size of every bowl will vary, so it helps if you’re flexible during the assembly process! Line the bowl with plastic wrap, extending up and over the sides of the bowl.
14. Use a sharp serrated knife to cut the Swiss roll into slices between ½ inch-1 inch thick. If you’re using a smaller bowl, you can make thicker slices, but if you’re using a larger bowl, you’ll need more pieces so you should err on the side of thinner cake slices.
15. Press the slices into the bowl, right up next to each other, covering the bottom and sides of the bowl. The cake slices can be squished together to get the most even coverage—the goal is to have as few gaps between cake slices as possible! When you get to the top of the bowl, you can cut the slices to fit the top of the bowl, re-roll them so they’re smaller, or otherwise manipulate them to get an even layer at the top of the bowl.
16. To make the filling, whip the cream and powdered sugar together until they form firm peaks. Spread a thin layer of whipped cream on the inside of the bowl—this will keep any of the filling from leaking through to the outside of the cake. Refrigerate the remaining whipped cream and the cake bowl.
17. Combine the gelatin and cold water in a small bowl, and whisk them together. Let the gelatin sit and absorb the water for about 5 minutes, then microwave for 15-20 seconds, until melted and liquid.
18. Combine the milk, almond meal, and granulated sugar in a saucepan, and bring to a simmer, stirring while the sugar dissolves. Remove the saucepan from the heat and whisk in the melted gelatin.
19. Fill a bowl or sink with ice water, and place the bottom of the saucepan in the cold water. Whisk while the milk cools until it is no longer warm to the touch. You want it to remain liquid, so don’t cool it so much that it starts jelling together, but it should be fairly cool to the touch when you’re done. Add the vanilla and almond extracts, if using, and stir well.
20. Fold the remaining whipped cream into the cool milk mixture. Stir in the freeze-dried strawberries, then pour the filling into the cake bowl—it will be fairly liquidy at this point.
21. If there’s a large gap between the top of the filling and the top of the cake along the sides, you can either trim the sides of the cake, or fill the gap with more sweetened whipped cream.
22. Finally, press the 9-inch round of cake on top of the filling, trimming it if necessary. Cover the top with plastic wrap, and refrigerate for at least 6-8 hours, or overnight, to set the filling.
23. To serve the cake, remove the plastic wrap from the top. Place a plate upside-down on top of the bowl, then invert the bowl so the cake rests on the plate. Gently lift the bowl up, and peel the plastic wrap from the top of the cake. This cake is best served chilled, and it can be kept in the refrigerator, well-wrapped, for up to a week.