In a medium bowl, combine the cooled, browned butter, 120g ground walnuts, granulated sugar, flour, egg white, egg, vanilla and salt. Mix to get a thick paste.
115 g (1/2 cup) unsalted butter, 120 g ground walnuts, 80 g (1/3 cup) granulated sugar, 40 g (1/3 cup) plain white flour, 1 egg white, 1 egg, 1/4 tsp fine table salt, 1 tsp vanilla extract