I preheat the oven to 350°F (175°C) and grease a 13×9-inch baking pan. In a large bowl, I whisk 2 cups flour, 2 cups sugar, 1 tsp baking soda, and 1 tsp salt. In a saucepan, I melt 1 cup butter with 1 cup water over medium heat, bringing it to a boil, then remove from heat. I pour the hot butter mixture over the dry ingredients, stirring until combined. I add ½ cup buttermilk, 2 eggs, and 1 tsp vanilla, mixing until smooth. I pour the batter into the pan and bake for 20–25 minutes, until a toothpick comes out clean. I let the cake cool completely in the pan.

In a saucepan, I melt ½ cup butter with ¼ cup buttermilk over medium heat, bringing it to a boil, then remove from heat. I gradually whisk in 3½ cups powdered sugar and 1 tsp vanilla until smooth and creamy.

I spread the frosting evenly over the cooled cake. I sprinkle holiday sprinkles generously for a festive look, ensuring every slice pops with color.

I cut the cake into squares and serve on a festive platter, perfect for holiday gatherings or cozy evenings.