Flourless Hazelnut and Pear Torte

Preheat oven to 375˚. Brush bottom and sides of a 9-inch spring form pan with oil. In a medium saucepan over medium heat, melt butter. Add brown sugar and cook, stirring occasionally, until bubbly and golden, about 4 minutes. Pour into spring form pan, spreading evenly with a spatula. Arrange pear slices in two layers, forming concentric circles over caramel. Grind hazelnuts in a food processor until a coarse meal forms. Add syrup, vanilla, lemon zest, and salt; blend until incorporated. With motor running, add eggs through feed tube; blend thoroughly for 5–10 seconds, being careful not to over process. In a medium bowl, beat egg whites until soft peaks form. Pour batter carefully into bowl with egg whites (off to one side). Using a spatula, fold egg whites into batter just until incorporated. Pour batter into prepared pan; place on a baking sheet or piece of foil and bake for 55–60 minutes, until a sharp knife inserted comes out clean. (Cover lightly with foil if it’s getting too brown.) Cool completely in pan. Run a thin knife around pan edge; invert onto a serving plate and carefully remove sides.