Make the caramel for the caramel cream. Heat the ☆ 30 g sugar and ☆ 2 tablespoons water in a pot over high heat.
When its color turns to amber, mix in 40 - 50 ml of the double cream, all at once. Be careful not to burn yourself, as it may splatter.
Place the pot on a well dampened cloth and let cool so it doesn't cook any more.
Line a 33cm square pan with parchment paper. Sift the flour twice, and set aside. Separate the eggs. Put the egg whites in a large bowl.
Add the ◇ 30 sugar, and the ◇ 20g trehalose to the egg whites, and beat with a whisk until it is glossy and soft peaks form. Be careful not to overbeat.
In a separate bowl, beat the egg yolks with the ◆ 30 g sugar until the mixture becomes a whitish color. It's a good idea to use a double-boiler.
Heat the milk in the microwave so that it's hot, but doesn't form a skin. Preheat the oven to 180℃.
Add the canola oil and milk to the mixture in Step 6, in that order, and mix well. Fold in the sifted flour by scooping up the batter from the bottom of the bowl with the whisk.
Add one large scoop of meringue from Step 5 to the batter in Step 8 with a whisk. Thoroughly fold into the batter with a rubber spatula, remembering to mix in the batter on the side of the bowl.
Next add 2 scoops of meringue and mix it in. When it's well blended, pour the batter into the bowl with the meringue and mix it all together.
Pour the batter into the baking pan and lightly smooth the top. Drop the pan from a height of about 10 cm to eliminate big air pockets.
Bake on the lower rack of the oven for about 13 -15 minutes at 180℃ (adjust the baking time according to the oven). Cool on a rack when it is done.
After 5 minutes or so,cover with a sheet of parchment paper to keep it from drying out,and let cool completely.
In the meantime, beat the cream leftover from Step 2 until soft peaks form. Add the cooled caramel from Step 3 and keep beating. Sweeten to taste with condensed milk or sugar.
When the cake has cooled completely, peel off the parchment paper. Decide which side will be on the outside, and cut off a thin diagonal slice about 3 cm wide on one edge.
In this photo, the top will be the start of the roll and the bottom will be the seam edge.Spread the cream evenly on the cake, except for the edge with the diagonal cut.
Done. This time I rolled up the cake with the browned side on the outside, but it's easier to roll up if you put the cream on the other side.
Same cake, but filled with milk cream (Recipe ID: 854880).
Made with butter, instead of canola oil, and filled with milk cream. It's lighter in color, and the butter makes it richer (recipe ID: 854880).
This is the canola oil I used. It's naturally bright yellow!
Story Behind this Recipe
I adapted my own recipe, taking hints from a famous rolled cake shop. I used Hiraide brand canola oil and the cake turned out a pretty yellow and looked and tasted delicious! It didn't have a funny taste like some vegetable oils, and it was lighter than ones with butter. This recipe is a keeper.
If you overbeat the meringue, it's hard to mix into the egg yolk batter, and you end up kneading it in,rather than folding. You may not need to use all of the cream.