Preheat oven to 350°F. Spray a 9x5 loaf pan with a nonstick cooking spray containing flour, or grease and flour it. Set aside
Whisk the flour, baking powder, and salt together in a medium bowl. Set aside.
In a large bowl, stir cooled melted butter, sugar and sour cream together. Add eggs, one at a time, vanilla and champagne. Stir in dry ingredients until just combined. Pour into prepared pan.
Bake for 35 to 45 minutes or until a toothpick comes out clean. The original recipe said 33-38 minutes. Mine took closer to 45 minutes, so just start watching it closely the last 10 minutes.
While cake is baking, prepare glaze. Add sugar and champagne together in a small sauce pan. Bring to a boil and cook for 1 minute. Remove from heat and allow to cool.
Cool cake in the pan for 15 minutes. Run a knife around edges of the pan and carefully remove the cake and place it on a cooling rack set over a baking sheet. Brush the champagne glaze over the top of the cake using a pastry brush. Let the cake finish cooling completely before frosting.
To make the frosting, whisk the powdered sugar, heavy whipping cream and 1 tablespoon of champagne together. Add more champagne as needed. Pour or spoon over pound cake. Chill to set.
Store loosely covered at room temperature for up to 3 days.