Make a moist butter cake by combining 3 cups of flour, 2 cups of sugar, 1 teaspoon of salt, 1 teaspoon of baking powder and 1/2 teaspoon of baking soda in a large mixing bowl. Preheat the oven to 325 degrees Fahrenheit, and butter a large baking pan.
Stir in 1 cup of buttermilk, 1 cup of butter, 2 teaspoons of vanilla and 4 eggs into the flour mixture. Stir the mixture in the bowl for about three minutes until it becomes a thick batter. Pour the batter into the greased baking pan, and bake it in the oven for about 60 minutes. Stick a wooden toothpick into the cake to see if it has cooked thoroughly. If the toothpick comes out with batter on it, the cake needs to stay in the oven for a bit longer.
To make the butter sauce that is poured over the cake, begin by cooking 3/4 cup of sugar, 1/3 cup of butter, 2 teaspoons of vanilla and 3 tablespoons of water in a large saucepan over medium heat. Remove the pan from the heat once all of the ingredients have melted together. Do not allow the mixture to boil or it may burn. Pour the butter sauce over the cake, and allow it to cool before serving.