Toast 1/2 a cup plus 2 Tbsp of the almond flour in the oven for 6 to 8 minutes, until golden brown. Watch carefully. In a mixing bowl sift together, the toasted and untoasted almond flour, cake flour, powdered sugar and a pinch of salt. Whisk together to incorporate ingredients. Add the egg whites and vanilla all at once and with the paddle attachment mix on medium speed for 3 minutes. Stop mixer and scrape sides of bowl to make sure everything is incorporated.