6-8tablespoonswater, room temperature (depending on the consistency you want - see tips in post)
Gel food coloring
Preheat oven to 350°F and line two baking sheets with nonstick silicon mats. Set aside.
In a large bowl of a stand mixer or using a hand mixer, beat butter and sugar until well combined and smooth (about 2-3 minutes).
Add egg, almond extract and vanilla extract and beat again to combine.
Add flour and baking powder (and a pinch of salt, if desired), and beat on low speed to start. As the dry ingredients incorporate, slowly increase the speed and beat until dough is combined and sticks together when pressed.
On a floured surface, roll out dough with a rolling pin about ¼" thick. Use cookie cutters to cut out shapes and place them on your prepared baking sheets. Keep in mind the cookies will not spread, so you can place them closer together than you would with other cookies. Re-roll the remaining dough (adding flour to your surface as needed) and continue cutting until you've used it all.
Bake for 7-8 minutes - I find 8 minutes to usually be perfect. You want to pull them out of the oven when they're not longer glossy, and before they start to brown.
Let cool on baking sheet for 5-10 minutes, then transfer to wire racks to cool completely.
In a large bowl using a stand mixer or hand mixer, combine powdered sugar, meringue powder, water, and almond extract. Beat on low speed, slowly increasing to high speed as the ingredients incorporate - about 4-5 minutes.
Lift the whisk from the bowl and take note of how long it takes for the icing that drops back in to meld back in to the rest - this will determine the consistency you'll be working with, and you can add water if it's too thick, or powdered sugar if it's too thin. See the tips in this post about the different icing consistencies.
If using gel food coloring: Transfer portions of your icing to small bowls and use a whisk to combine the color with the icing.
Transfer icing to piping bags fitted with piping tips, and start decorating!
Let decorated cookies set for at least 2 hours to let the icing completely dry, or move them to the fridge to speed up the process.
Serve and enjoy!
Cookie Storage: Store non-decorated or decorated cookies in an airtight container for 5 days at room temperature, or 2 weeks in the fridge.Freezing cookies: Store non-decorated or decorated cookies between layers of parchment paper in an airtight container for up to 3 months.Freezing dough: Prepare the dough through step 4, then flatten into a disc (or divide it in half and make it two discs), wrap in plastic wrap and place in a freezer bag for up to 3 months. When you're ready to make cookies, thaw at room temperature (about 1 hour) and roll out the dough.