In a large mixing bowl, cream together softened unsalted butter, confectioner's sugar, and a pinch of sea salt using an electric mixer on medium speed until light and fluffy, about 3-5 minutes.

Add the egg yolks and vanilla extract to the butter mixture and mix on low speed until thoroughly combined.

Divide the butter mixture into three equal portions in separate bowls. Add your chosen natural colorings to each portion and mix until uniform.

In a separate bowl, whisk together all-purpose flour and baking powder, then gradually fold into the colored cookie dough portions.

Shape the colored dough into three discs, wrap in plastic wrap, and chill in the refrigerator for 20-30 minutes.

Preheat the oven to 325°F (163°C). Shape dough into finger shapes, pressing a whole blanched almond at the tip for the creepy nail.

Freeze the shaped cookies for 40-60 minutes before baking.

Bake in the preheated oven for 20-25 minutes until the edges are lightly golden.

Let cookies cool on a wire rack; secure almonds with a touch of jam and decorate as desired.