This cake goes by several names. One is Kvæfjordkaka, or cake from Kvæafjord, a fjord in Northern Norway. It's also called Verdens Beste, or World's Best, and R says you're likely to find it at any celebration where the World's Best cake is necessary. He claims to remember there being one at his confirmation, and has a feeling his sister had one in addition to her wedding cake. It's appropriate, then, that R's sister translated their family recipe for us after our own wedding.
To tell you the truth, given how popular it seems to be in Norway, I can't imagine how it hasn't swept the world, in the way the Australian Pavlova has. If I were given the choice between the two, both being meringue-based desserts, I'd choose the World's Best any day. Before we get started, I should warn you. This is going to be one of those projects during which you're going to be sure that you've messed up along the way. You haven't. Just go with it, and it will turn out great.
A few notes on ingredients: Norwegians call egg yolks "egg plums" and I think that's just about the best descriptor you could ask for. I move that we adopt the name in English immediately. Secondly, the recipe calls for vanilla sugar, but Norwegian vanilla sugar isn't the granulated kind I've seen in the US. Instead, it's more of a vanilla-infused powdered sugar. So if you can't buy it, I'd make it by letting a vanilla bean sit in a bag of powdered sugar. Alternately, if you have granulated vanilla sugar, you could wizz it in your food processor of a few moments to powder it. Finally, the cream in the center is made party from a mix that is a Norwegian instant vanilla sauce. You can find it on Amazon, here. We bought it at the Norwegian Seaman's Church, here in NYC, which is actually also where we found authentic Norwegian vanilla sugar as well. If you want to substitute, just use a domestic instant pudding mix thinned with 1 to 1/2 cups of cream (we used 1 cup because it's best for the filling to be thick), or use a rum cake filling as I've seen suggested.
And now a note on equipment: When R's mother makes this, she does it in one large piece, which is then cut in half to make the bottom and top of the cake. We, however, have a little mini-oven, and decided to do it in two batches instead. We made it on two cookie sheets, and baked them on two racks in the oven, switching them half-way through.
Kvæfjordkaka, or Verden Beste, The World's Best Cake
For the Cake:
100 grams granulated sugar
100 grams butter
5 egg yolks
100 grams all purpose flour
1 teaspoon vanilla sugar (see note above)
1 teaspoon baking powder
Beat the butter and sugar until fluffy and light yellow. Add the egg yolks, the flour, the vanilla sugar and the baking powder and stir until combined. Line two cookie sheets with parchment paper. Divide the batter in half, and with a spatula, spread half of the batter on one of the cookie sheets in a very, very thin rectangle. I'd estimate that ours was about 6x8 inches. Do the same with the second half of the batter. Set aside. (You'll feel like your cake is totally wrong at this point, like it's too thin and sticky and hard to spread, and will never be a cake. You're wrong. It's just as it's supposed to be.) Set aside.
For the Meringue:
5 egg whites
200 grams of granulated sugar
100 grams of sliced almonds
Preheat the oven to 350F. In a clean bowl, with clean beaters, whip the egg whites. As they begin to thicken, add the sugar and continue to whip until it's thick and sticky and, well, a meringue. Divide the meringue in half. Pour half over one of the cake batters spread on the cookie sheets. Using a spatula, spread the meringue out over the cake, making a rectangle a couple of inches larger than the rectangle of cake batter. Sprinkle half of the almond slices on top. Repeat with the other half of the meringue, on the other half of the cake batter.
Bake in the oven for about 40 minutes until the meringue is cooked through. Remove from the oven and cool to room temperature.
For the filling:
Make a 50 gram package of instant vanilla sauce according to package directions. You do this usually by whisking boiling water into the powder to make a kind of pudding. But you want it quite thick, so use only a bit of water, probably not the full amount called for by the package. In another clean, cold bowl, whip 1 cup of heavy cream with the vanilla sauce. Once the cake is cooled to room temperature, flip one of the cake sides over so that the almonds are facing down. Layer the filling on top, then place the other cake side over that to create a sandwich. The second cake side should be almonds side up. Refrigerate, then serve. The cake can be made completely a day in advance and kept in the refrigerator.