To prepare Italian Butter Cookies start by adding in a container the diced butter and sugar. Work the two ingredients with a fork or your hands to combine them until you obtain a sort of lumpy cream. (Tip: Do not use a whisk to try to speed up the process or you'll cover the kitchen in sugar and butter.)
Add the whole egg, vanilla, flour, salt, and baking powder. Mix a little with a fork and then knead with your hands.
Continue working the dough on a work surface until you create a homogeneous dough ball.
Once you've obtained the ideal dough, cover it with plastic wrap and let it rest in the refrigerator for 30 minutes.
After the time has passed, take the dough, dust the work surface with flour, and roll it out with a rolling pin until it reaches a thickness of 3-4 millimeters (0.12-0.16 inches).
Preheat the oven to 180°C (356°F). Meanwhile, take a baking sheet, place parchment paper on it, and then go back to the dough to start cutting the butter cookies with your favorite cookie cutters.
As you cut the cookies, place them on the baking sheet, well spaced apart.
Compact the remaining dough scraps and roll it out again to make more cookies until all the dough for the butter cookies is used up.
The cookies should bake for 10-12 minutes in a preheated oven at 180°C (356°F). You can definitely take them out as soon as they start to have the ideal golden color.
Allow the butter cookies to cool for at least fifteen minutes before serving, dusted with powdered sugar, plain, or decorated.