Preheat the oven to 350 F.
In the bowl of a stand mixer use the paddle attachment to beat the butter and sugar together at medium-high speed for 1 minute. (Or beat by hand or use hand held electric mixer.)
On medium speed, beat in the egg, vanilla, almond extract, baking powder and salt.
Measure the flour correctly (see note) and add to the mixer 1 cup at a time, beating until combined after each addition.
Don't chill the dough!!! Divide it into two balls and roll out to exactly 1/4" thick on a clean piece of parchment paper using just enough flour on your rolling pin to prevent sticking. Scraps of dough can be gathered up, kneaded together until they are a uniform ball and then rolled out again. Repeat as needed until used up.
When removing cut cookie dough from the parchment paper use a thin, flexible metal spatula. Quickly slide the spatula under each cookie and use the spatula to put the cookie on the baking sheet.
Line cookie sheets with clean parchment paper. Space out cookies on sheets with enough room to rise. Bake at 350F for 6-8 minutes. The cookies will not be brown at all. They will be dead white but look set. (For crisp cookies instead of soft bake an additional 2-3 minutes until edges start to brown.)
After removing from the oven let the cookies cool on the sheets for several minutes until firm enough to move without breaking. Use a spatula to put the cookies on a wire rack. Cool completely before frosting.
Decorate with vanilla buttercream (below) and store tightly covered for up to five days.