The Bojon Gourmet

Bake the cake:
1 Position a rack in the center of the oven and preheat to 350º (or 375º for small cakes). Grease a 6" round cake pan with 2" high sides with softened butter, line with a round of parchment paper, and grease the parchment (or dust the greased pan with a bit of buckwheat flour and tap out the excess).
2 Combine the butter and vanilla bean pod and scrapings in a medium saucepan. Cook over medium heat, swirling occasionally, until the butter browns and smells nutty, 5 - 10 minutes. The butter will foam up, and the milk solids on the bottom of the pan should be a rich brown color, not black. The rest of the butter will remain golden-amber. Watch it carefully, as it can go from brown to burnt in little time. Remove from the heat and let cool sightly.
3 Meanwhile, spread the hazelnuts on a small, rimmed baking sheet and toast in the oven until slightly darkened, 10-12 minutes. Let cool enough to handle, then rub between your hands to flake off as much of the papery skins as will easily come off. Let the nuts cool completely.
4 Finely grind the toasted, rubbed, and cooled hazelnuts with the flour, powdered sugar and salt in a food processor (or a coffee grinder in batcheuntil floury in consistency.
5 In a heatproof metal bowl, combine the egg whites and granulated sugar. Place the bowl over a low flame (or a pot of simmering wateand whisk until the whites are warm to the touch and the sugars are dissolved. Remove from the heat, and whisk in the nut mixture. Place the bowl on a damp towel to secure, and gradually whisk in the warm butter, 1/4 cup at a time, so that the mixture emulsifies. You will have a fairly loose batter, brownish-grey from the hazels and buckwheat. (The batter can be baked directly, or stored in the fridge for several days.)
6 Scrape the batter into the prepared pan(and bake until puffed and golden, and a toothpick inserted in the center comes out clean, about 35 minutes for a 6" cake, and less time for smaller cakes.
While the cake bakes, prepare the apples:
1 Peel the apples (I like to use a t-shaped vegetable peeleand cut them off the core, then into 1/2" wedges. Melt the 2 tablespoons butter in a wide, heavy-bottomed skillet over a medium-high flame. Add the sugar, swirling to combine, then the apples. Let the apples sit for a minute or two to sear, then toss them. Repeat the searing and tossing for 10 minutes or so, until the apples are very soft and very golden (watch them more closely toward the end as they will caramelize more rapidly). Remove from the heat and pour over the cider or whiskey, stirring and scraping any browned bits, then stir in the rosemary. (The apples can be made ahead and stored in the fridge - re-caramelize in a pan before serving.)
2 Let the cake cool 10 minutes, then invert it onto a plate and peel off the parchment. Sprinkle with powdered sugar and serve warm or at room temperature with a mound of glazed apples and a scoop of softly whipped cream.
3 The cake keeps well for up to 4 days, at room temperature, in an air-tight container.