Preheat the oven to 350°F. In a medium bowl, add flour, baking powder and salt (measuring the flour with a scale is the most accurate). Using a whisk, stir to combine and get the lumps out. Set aside.In a large bowl, add butter and sugar. Beat with an electric mixer for 3 minutes. Add the egg and vanilla and beat another minute. With the mixer on low, gradually add the flour mixture.Blend until the dough begins to pull away from the sides of the bowl. Take the dough out of the bowl and place on a large piece of parchment paper. Use your hands to knead the dough for a few minutes. Divide the dough into two sections and wrap with parchment paper.To roll dough, place another piece of parchment paper on top of dough and roll with a rolling pin until the dough is between ⅛" and ¼" ...