9 egg yolks
14 T. sugar
2 sticks butter (1 c.)
1/2 vanilla bean, seeds scraped out, pod discarded
1/4 tonka bean, grated
1/2 c. flour
1/2 c. cornstarch
Combine egg yolks, whole egg, sugar, vanilla seeds and grated tonka in the bowl of a stand mixer and beat on medium speed for 20 minutes. The mixture will increase in volume, thicken and turn white. Yes, beat for 20 minutes.
Meanwhile, melt the 2 stickes of butter and let cool a bit. Use another blob of butter to grease a 9 x 5 loaf pan well. Cut a piece of parchment or wax paper to fit the bottom of the pan, place it in and then butter the paper too. Preheat the oven to 375°.
Sift together the flour and cornstarch. After you've beaten the eggs for 20 minutes, on low speed beat in the flour/cornstarch mixture just until combined. With the beater running on low, slowly pour in the melted butter. When it's all combined, turn the mixer to high for 10 seconds, then turn it off.
Pour the mixture into the prepared pan and wrap completely and tightly with a single layer of aluminum foil. Make sure not to make the foil thick on the bottom. Bake for 55 minutes. Remove from oven, unwrap. (When the cake is done the top will be nicely browned but quite light and tender.)
Immediately invert the pan onto a flat plate or platter. Lift the pan off, peel off the parchment, and lay a piece of plastic wrap over the cake while it cools.
Slice thinly and serve as is, or with a bit of whipped cream, a few berries or a couple of spoonfuls of warm berry compote. Even a little scoop of ice cream. But don't overwhelm the Sableuse. You want the delicate texture and nuanced flavors of the vanilla and tonka to shine through.