It is a shame I didn't get pictures of this in the end, it looked really nice cut into slices. I fell in love with roll cakes ("ro- ru kei-ki" in native Japanese!) in Japan- you can find any manner of these cakes in the depachika stores under department stores at the train station hubs.
Make sure you have the right size pan (rectangular enough to facilitate rolling from one side), I used a 12x 17 inch pan, Joy of Cooking states a 10.5 x 15.5 pan works too. Also, make sure you have wax paper/parchment or foil, otherwise I think this would be impossible.
Since you need to beat the yolks and whites separately, plan for separate bowls and mixers/beaters so you don't contaminate the whites with fat from the yolks.
1. Crack and separate 4 eggs- it is easiest to do this when cold, so I did this first and then waited to beat them (book says to wait until they are 70 degrees). As usual when working with egg whites, make sure none of the yolk gets into your egg white bowl. I stuck the whites in my stand mixer (in preparation for beating them into peaks), and the yolks into a pyrex measuring cup.
2. Find and measure pan- grease, line with foil overhanging edges, grease again (believe me on this). Preheat oven to 375 F.
3. Beak the 4 egg yolks from step 1 until light yellow
4. Gradually add 3/4 C granulated sugar and keep beating until gets thick and creamy- it will change consistency
5. Add 1 tea vanilla and mix
6. In a medium bowl, sift or break up the clumps in 3/4 C cake flour, 3/4 tea baking powder, and 1/2 tea salt.
7. Add the egg yolk/sugar mixture with the flour mixture and beat until "smooth", mine was quite thick.
8. In separate clean bowl, beat egg whites until stiff but not dry
9. Carefully fold egg whites into other mixture in two batches
10. Pour into prepared pan, bake 12 minutes
11. Remove from oven, pull foil and cake out of pan. Cut off hard/crunchy ends from the cake and use a knife to peel cake off of foil. I flipped the cake over for the shiny top would be on the outside of the cake.
12. Use foil to carefully roll cake into the shape, so when it cools you can re-roll with the filling.
13. Beat 1 small container of whipping cream until thick. Add 1/2 C of raspberry jam and 1/2 tea vanilla.
14. Spread raspberry cream inside cake, carefully re-roll with seam at bottom.
15. Move cake to final plate or serving dish, frost with additional raspberry cream. Refrigerate before serving.