Preheat the oven to 350°F (175°C). Grease a 10- to 12-cup bundt pan thoroughly and dust lightly with flour, tapping out excess.

In a large bowl, whisk together 2 cups flour, 1 1/2 cups sugar, 1/2 teaspoon salt, and 1 tablespoon baking powder until evenly combined.

Add 1 cup softened unsalted butter, 4 large eggs, 1 tablespoon vanilla extract, and 1 cup buttermilk to the dry mix. Beat or mix just until smooth and homogenous—scrape the bowl once or twice. Do not overmix.

Pour the batter into the prepared bundt pan and smooth the top. Bake in the preheated oven for 45–50 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs.

While the cake bakes, melt 1/2 cup unsalted butter in a small saucepan over medium heat. Add 1 cup granulated sugar and 1/4 cup water. Bring to a boil, then reduce heat and simmer gently for 5 minutes, stirring occasionally. Remove from heat and stir in 1 tablespoon vanilla extract. Let the sauce cool slightly but keep it warm.

When the cake is done, let it rest 5 minutes in the pan. Then invert the cake onto a cooling rack set over a baking sheet or platter to catch excess syrup. Immediately spoon the warm butter sauce evenly over the top, letting it drizzle and soak into the crevices.

Allow the cake to cool until the sauce firms slightly and the cake is mostly at room temperature—about 1 hour. For best slices, cool completely.

Serve on its own or with whipped cream or vanilla ice cream.