Grease two 8 or 9-inch square pans. Set aside 2 tablespoons of the dry muffin mix. In large bowl, dissolve yeast in warm water (105 to 115°F.). Lightly spoon flour into measuring cup; level off. Add remaining dry muffin mix, 2 cups of the flour, soup and 1/4 cup of the melted butter; mix just until dry ingredients are moistened. Gradually stir in remaining 2 cups flour to form a stiff dough. Knead on floured surface until smooth, about 1 minute. Cover; let rest 15 minutes.