In a microwave-safe bowl, add the chocolate and (1/4 cup) milk, and microwave until softened. Mix well for about 20 to 30 seconds.
In a large bowl, cream together the butter and sugar, slowly add the eggs, beating after each egg.
In another bowl, mix the flour, baking powder, and salt, fold in the sour cream, 1/4 cup of milk, and the vanilla extract.
Mix the butter/sugar with the flour mixture, mix well. Divide the batter into two bowls, and pour the chocolate into one bowl, mixing well. Mix the chocolate chips into the vanilla batter.
Grease your loaf pans with cooking spray, pour the vanilla batter down first, and then drizzle the chocolate batter on top.
Set the loaf pans into the air fryer basket for 15-20 minutes at 320 degrees F, air fryer setting. Check the breads to make sure that they are fully cooked before removing them.
Plate, serve, and enjoy!