Preheat oven to 350 degrees. Butter and flour two 8-inch round cake pans; set aside. In a food processor, combine nuts, flours, sugar, and salt; pulse until nuts are finely ground but not oily. Add the butter, oil, lemon zest, and lemon juice; pulse until the mixture just comes together.
Divide the mixture between the two pans and press in until even. With a sharp knife, cut each round of dough into 8 wedges. Lightly prick the tops with the tines of a fork. Bake until set and pale tan, about 22 minutes.
Transfer to a wire rack and cut through each wedge. Cool 10 minutes, then invert onto a plate and transfer to a wire rack to cool completely.