. In medium bowl, whisk the flour, baking powder, baking soda, and salt. In a stand mixer fitted with the paddle attachment or with a hand mixer, beat the butter and sugar on medium-high until well blended and fluffy, about three minutes. Add the eggs, one at a time, beating on medium speed until just blended and ending the orange zest and vanilla with the second egg. Using a wide rubber spatula, fold in half the dry ingredients, then the over, and then the remaining dry ingredients. Scrape the batter into the prepared pan and spread evenly. Bake for 15 minutes.