Preheat the oven to 325F.
Mix the Butter, Sour Cream, and Sugar in a stand mixer until well combined.
Beat in the eggs, one at a time.
Beat in the orange zest, vanilla, and baking powder.
Gradually add the flour, beating until well combined.
In a buttered bundt/loaf pan or in muffin/cupcake wrappers, pour the batter. Make sure to leave room for it to rise (it can be a lot).
A loaf/bundt should bake for about 1.5 hrs and a 12 muffin tray for about 30 minutes.
Remove and allow to cool.
To make the glaze whisk all of the ingredients into a thick paste adding more sugar if needed.
Drizzle over the cooled muffins.