unsalted butter, room temperature • (1.75 oz, 5.5 Tbsp) powdered sugar • (1 oz, 2 Tbsp) beaten egg, room temperature • (4.2 oz, 1 us cup) cake flour, or all-purpose flour • vanilla oil, optional • unsalted butter, room temperature • (1.75 oz, 6 Tbsp) brown sugar • (1.6 oz, 3 Tbsp) beaten egg • (1.75 oz, 8.5 Tbsp) ground almonds • cake flour, or all-purpose flour • rum • sweet roasted chestnuts •