Preheat your oven to 325°F (163°C) and grease a 13x9 inch glass pan with butter or cooking spray.

In a large bowl, whisk together all-purpose flour, sugar, salt, baking powder, and baking soda.

In another bowl, whisk together buttermilk, whole eggs, egg yolk, vanilla extract, and vegetable oil.

Gradually add room temperature butter to the dry ingredients and mix until resembling coarse crumbs.

Incorporate the wet mixture into the dry ingredients, mixing gently until just combined.

Pour the batter into the prepared pan and bake for about 45 minutes until golden brown.

Cool in the pan on a wire rack for 15 minutes.

Prepare the glaze by melting butter in low heat, adding brown sugar, vanilla extract, and buttermilk, then stir in confectioner’s sugar.

Poke holes in the cake and pour the warm glaze over, letting it soak for 30 minutes.

Slice into squares and serve with fresh berries or a scoop of ice cream.