Preheat your oven to 325°F (160°C) and grease a 9-inch round cake pan.

In a large bowl, beat the butter and sugar together until fluffy. Add the eggs one at a time, mixing well after each.

In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.

Gradually mix the dry ingredients into the butter mixture, alternating with the buttermilk and vanilla extract, until well combined.

Pour the batter into the greased pan and bake for 45-50 minutes, or until a toothpick inserted in the center comes out clean.

While the cake bakes, prepare the glaze by combining butter, sugar, water, and vanilla in a saucepan. Cook over low heat until the sugar dissolves and the mixture thickens.

Once the cake is done, let it cool in the pan for about 5 minutes, then transfer it to a wire rack to cool completely.

After the cake has cooled, drizzle the glaze on top, letting it spill over the sides.

Slice and enjoy your homemade butter cake!