• combine flour, baking powder, + salt, whisk
• cream butter, shortening, both sugars in a bowl, until smooth
• add egg + almond extract until blended. add half the flour mixture, beat to combine. add the rest of the flour. stir in nuts.
• divide dough in half + wrap separately in platic wrap, pressing dough into a rectangle. chill for 2 hours.
• stir together jam and cornstarch(arrowroot) in a small saucepan, bring to a boil and simmer for 5 minutes. cool 20 minutes then cover and put
in fridge for 1 hour.
• roll one portion at a time, on parchment to form a 10×12″ rectangle, 1/8″ thick, thinly spread 1/2 jam over the dough, leaving a 1/2″ border. roll into a log.
wrap in parchment. repeat with other dough and chill for 24 hours.
• preheat oven to 350*, line baking sheets with parchment. cut well chilled dough into 1/2″ slices, transfer to baking sheets and space 2″ apart.
• bake until edges are lightly browned, 15-17 minutes. transfer to a wire rack.