Make dough: Pulse almonds with 1/4 cup flour until finely ground (be careful not to grind to a paste). Beat together butter and brown sugar with an electric mixer at medium speed until pale and fluffy, about 3 minutes. Reserve 1 Tbspn beaten egg, chilled for egg wash and beat remaining egg into butter mixture, then add vanilla and almond extracts, beating well. At low speed, mix in almond mixture, zest, salt, and remaining 1-3/4 cups flour until mixture just forms a dough. Halve the dough and form each half into a 5-6 inch disk. Wrap disks separately in plastic wrap and chill until firm, at least 30 minutes.