Hazelnut Brown Butter Cake

Preheat oven to 350 °F.

Spread the hazelnuts on a baking sheet, and toast for 12 to 15 minutes, until they're golden brown and smell nutty. Let them cool.

Cut out a circle of parchment paper to fit in the bottom of a 10-inch round cake pan. Brush the pan with a little melted butter and line the bottom with the paper.

Place the rest of the butter in a medium saucepan. Slice the vanilla bean lengthwise down the center, and use a paring knife to scrape the seeds and pulp onto the butter. Run the vanilla-coated knife through the butter to capture all seeds. Add the vanilla pod to the pan, and cook the butter until it browns and smells nutty (about 6 to 8 minutes). Frequently scrape the solids off the bottom of the pan to ensure even browning. Set aside to cool. Remove and discard the vanilla pod.

Grind the hazelnuts with the confectioners’ sugar in a food processor until finely ground. Add the flour and pulse to combine. Transfer to a large bowl.

Place the egg whites in the bowl of a stand mixer fitted with the whisk attachment. Add the granulated sugar and mix on high speed for 4 to 5 minutes, until the mixture forms very stiff peaks.

Alternate folding the dry ingredients and the brown butter into the egg whites, a third at a time. Scrape the bottom of the brown butter pan with a rubber spatula to get all the little brown bits.

Pour the batter into the prepared cake pan, and bake for 50 to 60 minutes. Cool on a rack for 30 minutes. Run a knife around the inside edge of the pan, and invert the cake onto a plate. Peel off the paper, and turn the cake back over onto a serving platter. Sprinkle with powdered sugar or cover with ganache.

For the ganache: Melt the chocolate, heavy cream, and coffee in the top of a double boiler over simmering water until smooth and warm, stirring occasionally. Drizzle over the top of the cake.