Step 1

Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13-inch baking dish.

Step 2

Combine flour, sugar, baking powder, and baking soda in a large bowl. Cut butter into flour mixture until mixture resembles coarse crumbs. Reserve about 1 cup butter crumbs.

Step 3

Stir buttermilk, eggs, and vanilla extract into remaining crumbs until batter is just combined; pour batter into prepared baking dish. Sprinkle reserved butter crumbs over batter.

Step 4

Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 35 minutes.