Slice off the ends of the bread and cut it into thick slices, then cut those slices into cubes to make about 5 cups of bread cubes.
Melt the butter and the oil together in the microwave, then pour the mixture into a bowl. Add the minced garlic and chopped parsley, and toss the bread cubes in the bowl until they are well coated with the mixture.
Preheat the air fryer to 400°F (200°C). Arrange the bread cubes in a single layer in the air fryer basket and air fry for 2 minutes. Give the basket a shake, then continue air frying for another 2-3 minutes, depending on how browned you like your croutons.
Once done, transfer the croutons to a bowl and let them cool down to crisp up.
Notes
Store in an airtight container or a bag for up to a week. When ready to eat, air fry the croutons at 375F for a minute or two to crisp up.