Preheat oven to 350ºF and prepare quarter sheet pan with grease and parchment. Set aside.
In a medium bowl, add all-purpose flour, baking powder, salt, and spices and whisk to combine. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, add butter, granulated sugar, and light brown sugar. Beat on medium-high speed until pale in appearance and fluffy.
Add eggs and continue mixing on medium speed until incorporated. Add molasses and vanilla extract and mix to incorporate. Add buttermilk and mix to incorporate. Add flour mixture and mix on low until combined, with no visible dry flour. Pour batter into prepared quarter sheet pan and spread evenly.
Bake until a toothpick inserted into the center comes out clean (with maybe a few crumbs), approximately 20-25 minutes. Remove from oven and set aside to cool in the pan for 15 minutes before removing from pan to cool completely.