In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar, on medium speed, until fluffy, 3 to 4 minutes, stopping to scrape sides of the bowl.

Add egg, egg yolk, almond, and vanilla extract beat until completely combined.

Whisk the flour, baking powder, and salt together in a medium bowl.

Turn the mixer down to low and add flour mixture, beating until just combined. If there are any leftover dry ingredients on the bottom of the bowl, use a rubber spatula to fully incorporate the last bits of flour.

Divide the dough into 2 equal parts. 

Roll out each part of the dough on a sheet of baking paper to about 1/4 inch thick, lightly dusting the surface as you roll if needed to prevent the dough from sticking to your rolling pin.

Transfer the rolled dough with paper onto a baking sheet, and stack the second dough (with paper) on top, cover lightly, and refrigerate for at least 1 -2 hours or overnight.

Once chilled, preheat oven to 350 degrees F.

Line 2 baking sheets with parchment paper or silicone baking mat.

Remove one of the dough pieces from the refrigerator and use a cookie cutter to cut out desired shapes. Re-roll the remaining dough and continue cutting until all is used.

Transfer to the baking sheets and bake, one sheet at a time, for 10 minutes until very lightly colored on top and around the edges.

Let cool on the baking sheet for 5 minutes, then transfer to a wire rack to continue cooling.

Cool completely before icing.

For the icing, in a large mixing bowl, whisk together the powdered sugar and meringue powder.

Add water, 4 tablespoons at first, and mix until smooth and glossy.

Add 1 more tablespoon of water if the icing is too thick. It should be runny with a consistency of a bit thinner than glue.

Transfer the frosting to a piping bag with a small round tip for piping thin lines and decorate cookies as desired.

Sprinkle with sprinkles of your choice