Preheat the oven to 350°F/180°C, or 160°C fan oven. Prepare a cookie sheet by lining it with parchment paper or silicone mat and set aside.
In a bowl of a stand mixer fitted with the paddle attachment, cream the butter with the sugar until smooth, light in color and creamy (2-3 minutes).
Add vanilla and egg and mix again until the egg is incorporated but don’t over whip (the longer you whip the egg, it can souffle up and the cookies will rise and you don’t want that).
Add in the flour, baking powder, and salt and mix again until just combined. Scrape the sides with a spatula so no dry flour is left. The cookie should pull away from the sides of the bowl (if it doesn’t add ½ cup of flour).
Divide the dough into 4 portions, and roll out each using a rolling pin into ¼ inch thickness. Cut out using a cookie cutter and with the help of a offset spatula transfer to the cookie sheet.
Bake for 8-9 minutes rotating at 6 minutes for even browning (one sheet at a time). Allow to cool on the cookie sheet for 5 minutes, then transfer to a wire rack. Cool completely before icing the cookies.
Notes
This cookie recipe will make approximately 36 cookies using a 4 inch (10cm) cookie cutter. You may get more or fewer cookies depending on the shapes that you make.
To Store: Undecorated cookies will stay fresh for up to 1 week if you'd like to make the cookies one day and then decorate them later.
To Freeze: Seal the cookies in an airtight container with a layer of parchment or wax paper between layers. Decorated and undecorated sugar cookies will keep in the freezer for up to 3 months.