Note from Ricardo The buttermilk can be replaced with 1/2 cup (125 ml) milk mixed with 1 ½ tsp (7.5 ml) white vinegar or lemon juice. Let sit for 5 to 10 minutes. Stir before adding to the recipe. The muffins can be reheated in an air fryer for 2 minutes at 400°F (200°C).