Preheat your oven to 350°F (175°C). Grease your 9x13 inch baking pan with butter or line it with parchment paper to prevent sticking and make it easy to lift the squares out once baked.
In a medium bowl, whisk together the all-purpose flour, ground ginger, ground cinnamon, baking soda, and salt. This ensures the spices and leavening agents are evenly distributed throughout the batter.
In a large bowl, use an electric mixer to cream the softened unsalted butter with the brown sugar and granulated sugar until light and fluffy. This process incorporates air, helping to create a tender crumb in the final cake.
Beat in the eggs one at a time, making sure each is fully incorporated before adding the next. Then, mix in the unsulfured molasses and vanilla extract until the mixture is smooth and glossy.
Reduce the mixer speed to low. Add the dry ingredients in three additions, alternating with the buttermilk in two additions, beginning and ending with the dry ingredients. Mix just until combined—avoid overmixing to keep the cake tender.
Pour the batter evenly into your prepared baking pan. Smooth the top with a spatula. Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool completely in the pan on a wire rack. Once cooled, cut into neat squares. These Gingerbread Snack Cake Squares are now ready to enjoy!