Preheat your oven to 325° F. Butter and flour a 9-inch loaf pan.
In a stand mixer or bowl, cream together the sugar and butter until very light and fluffy, 3 to 5 minutes. Add the eggs one at a time, beating between each one. Add in the vanilla and mix to combine.
In a separate bowl, whisk together the flour, baking powder, and salt.
Add the flour mixture to the wet ingredients, beating until just incorporated. Pour the batter into the prepared loaf pan, smooth the top, and bake for 55 to 70 minutes, or until a cake tester inserted in the center comes out clean.
While the cake cools, whisk together all of the glaze ingredients (add more milk, depending on how thin you want the glaze to be). Turn the cake out onto a cooling rack, and drizzle the glaze over the top. Wait for the glaze to set before slicing and serving the cake.