Begin by creaming together confectioners' sugar and unsalted butter until pale and fluffy. Add egg, almond extract, green food coloring, and blend until smooth.

In a separate bowl, whisk together all-purpose flour and kosher salt. Gradually add flour mixture to butter blend, mixing until a soft dough forms.

Fold in finely chopped pistachios. Cover dough with plastic wrap and refrigerate for at least 30 minutes.

Scoop dough and roll into finger shapes, about 3 inches long. Press sliced almonds onto one end and pinch to form knuckles.

Freeze shaped cookies for 30 minutes. Preheat oven to 375°F and bake cookies for 7-9 minutes until edges feel firm.

Once cooled, replace almond fingernail with jam to mimic blood. Let rest before serving.