Non-stick cooking spray
1 cup sour cream
2/3 cup milk
1 teaspoon finely grated orange zest
Heat oven to 350°F. Coat the bottom of an 8 x 4-inch loaf pan with no-stick cooking spray.
Stir muffin mixes, sour cream, milk, and orange zest in a large bowl until evenly moistened. Spread evenly in the prepared pan.
Bake for 50 to 55 minutes or until a toothpick inserted into the center comes out clean. Cool in the pan for 10 minutes. Remove to a wire rack to cool completely.