Preheat oven to 375 degrees F (190 degrees C). Line a baking sheet with parchment paper.

Whisk flour, poppy seeds, baking powder, and salt together in a bowl.

Beat butter and sugar together in a stand mixer until light and fluffy, 3 to 5 minutes. Beat in vanilla extract and whiskey. Add the flour mixture; beat until dough is just combined and crumbly.

Chill dough in the refrigerator until set, about 10 minutes.

Divide dough into 4 portions. Roll 1 portion of dough into a tube on a floured work surface; cut into 1-inch pieces. Place onto prepared baking sheet. Repeat with remaining dough. Flatten dough pieces to about 2 inches long and 3/4-inch wide.

Press the flat side of a butter knife into 1 end of the dough pieces to make a small dent; dot with jam. Place almond slivers onto jam. Score 2 sets of slits with a knife to create knuckles.

Bake in the preheated oven until golden, about 7 minutes. Cool for 10 minutes before transferring to a wire rack to cook completely, about 20 minutes.