Whisk together flour and baking powder; set aside.
Cream butter, vanilla extract, and sugar. Add eggs one at a time, mixing well.
Add flour mixture; mix to combine. Knead until firm. Chill dough for 1 hour.
Preheat oven to 375°F (190°C) and line baking sheets.
Shape cookies into 1-inch balls or swirls. Place on baking sheets.
Bake for 8-10 minutes. Cool completely on wire racks.
Combine powdered sugar, vanilla extract, and milk for the glaze. Dip cookie tops in glaze and decorate with sprinkles.
Let set for 30-60 minutes. Enjoy!
Notes
Use room-temperature butter for a smooth, even dough. To soften butter quickly, cut it into smaller pieces and let it sit at room temperature for about 15-20 minutes
Once you add the ingredients mix just until combined. Overmixing can lead to dense, tough cookies, which is not ideal for soft Italian Christmas cookies.
Do not skip chilling the dough. It makes it easier to handle and shape the dough. This also helps the cookies keep their shape while baking.
Decorating warm cookies can cause the icing to melt or the decorations to slide off.
Store cookies in an airtight container at room temperature for up to a week. You can freeze baked cookies for up to 3 months. Thaw them at room temperature before serving. It is best to freeze them without the glaze and decoration.