Preheat the oven to 450 degrees F. If you’re using a dark (darker than silver) muffin pan, use 400 degrees F. Grease 24 muffin cups or line with paper liners.Beat butter and sugar with an electric mixer until light and creamy. Beat in vanilla, eggs, salt and baking soda. Fold in the sour cream, then fold in the flour and any add-ins you choose (see below).Divide batter evenly between the muffin cups and bake for 15 minutes at 450F or about 23 minutes at 400F.