Preheat the oven to 350º. Line a 9-inch square baking pan with a 12-inch-long sheet of foil. Using a food processor, mix the flour, almonds, sugar, baking soda and salt until the nuts are finely ground. Add the butter and pulse until coarse crumbs form. Beat together the egg and vanilla and drizzle over the dough mixture. Transfer the mixture to a large bowl and knead with your fingertips until clumpy.