Preheat the oven to 400 degrees.
In a medium bowl, cream your butter and sugar. Make sure your butter is softened but not melted. You can use a hand mixer or a metal spoon.
Add the vanilla and egg and mix well.
Add the flour, baking powder and salt and combine.
Divide the dough in half and form one half into a ball shape. It doesn't have to be perfect. Flour your surface well. (I use my flour sifter.)
Place the ball in the middle of the flour. Roll the dough out to about 1/8" thick.Then remove the plastic wrap and place your cookie cutters on the dough. I try to make as many cookies as possible out of each sheet of dough so I'm not adding too much flour to the dough each time it gets rolled out.
Using a spatula, place your cookies on your cookie sheet.
Bake cookies in oven for 6-8 minutes. You don't want them to brown. If you're not sure they are done, softly press on one and if it still soft, keep it in for a little longer. They will feel mostly firm when they are done.
Remove them from the oven and let them rest for a minute or two and then place them on a cooling rack or muslin type cooling cloth. Allow them to cool completely.
If you want to frost them the same day, you can leave them out. If you want to wait a day, store them in an airtight container on the counter.