How do I make lactose-free blueberry muffins?
Replace butter with oil.
Replace milk or cream with the same amount of soymilk or other non-dairy beverage. (Orange juice works well too!) For a 12 muffin recipe, add about 1 tsp apple cider vinegar and 1 tsp lemon juice. Use molasses in place of the lemon juice if you'd like a stronger flavor.
Basically, you're replacing the acid in your recipe. Usually, buttermilk or sour cream is used in muffins to react with the baking powder and/or baking soda to achieve lift. You're adding acid (vinegar and lemon juice) to trigger the same reaction, and filler (soymilk or orange juice) to keep the wet/dry balance in place.