Preheat the oven to 350°F and butter a bundt pan with butter.
Coat the pan with sugar.
Sift together flour, baking powder, baking soda, and salt.
Beat butter and sugar. If using vanilla seeds, add to sugar first.
Add vanilla extract.
Add 3 eggs, one at a time.
Add the flour mixture.
Add sour cream, orange zest, and orange juice.
Transfer the batter to the bundt pan. Bake for about 45 minutes.
Let cool for 10 minutes then flip the cake out of the pan while still warm.
Make a glaze by combining powdered sugar, butter, and boiling water. Pour over the cake and let set before serving.