- 1 cup (about 4 ounces) blanched whole hazelnuts, lightly toasted and skinned
- 1½ cups sugar
- 1 cup all-purpose flour (spoon flour into dry-measure cup and level off)
- 10 tablespoons (1¼ sticks) unsalted butter
- 2 tablespoons dark rum
- 2 teaspoons vanilla extract
- 1 cup egg whites (from 7 or 8 large eggs)
- Pinch of salt
- Confectioners’ sugar for finishing
- One 2-inch-deep 10-inch round cake pan, buttered and bottom lined with buttered parchment or wax paper
- Position a rack in the middle of the oven and preheat to 350 degrees.
- Pulse the hazelnuts and ¾ cup of the sugar in a food processor until the nuts are finely ground. Pour into a bowl and stir in the flour.
- Melt the butter over low heat and continue to cook for a minute or so, until it turns a light golden color. Remove from the heat and let cool, then add the rum and vanilla.
- In the clean, dry bowl of a heavy-duty mixer fitted with the whisk, beat the egg whites with the salt until they form a very soft peak. Beat in the remaining ¾ cup sugar in a very slow stream, and continue beating until the egg whites hold a soft peak again.
- Beginning with the hazelnut mixture, alternately fold in the hazelnut and butter mixtures, one-third at a time. Pour the batter into the prepared pan and smooth the top.
- Bake for about 50 minutes, until the cake is well risen and golden. The center should feel firm when pressed with the palm of your hand.
- Cool the financier briefly on a rack, then unmold and remove the paper. Turn the cake right side up to finish cooling.
- Just before serving, dust very lightly with confectioners’ sugar.