Set aside 36 whole sliced almonds to use as fingernails later. Take the rest of the almonds and pulse them in a food processor until they're finely ground, almost like coarse flour. This adds a subtle nutty texture throughout the shortbread base.
In a large bowl, beat the cream cheese, butter, powdered sugar, almond extract, and salt together until the mixture turns light and fluffy. This usually takes about two to three minutes with a mixer running on medium speed.
Gradually beat the flour into the creamed mixture until a dough forms. Stir in the ground almonds by hand at the end. The dough will be quite stiff, which is exactly what you want for shaping sturdy fingers.
Preheat your oven to 325°F. Roll about one tablespoon of dough between your palms into a three-inch finger shape. Place each one two inches apart on a greased or parchment-lined baking sheet.
Press one reserved almond firmly into one end of each finger to form the fingernail. Use a sharp paring knife to make three shallow crosswise slits along the middle of each finger to look like knuckles.
Bake for 15 to 20 minutes, or until the edges turn lightly golden. Let the cookies rest on the baking sheet for a few minutes before carefully transferring them to a wire rack to cool completely.