Cut the bread into 1/2 inch cubes. Place the cubes into a bowl.
In a separate microwave-safe dish, place the butter into it and cover it with a paper towel.
Microwave the butter for 35 seconds. Remove the butter and add 1 Tbs dry ranch dressing mix.
Mix the butter and ranch dressing together, then drizzle over the top of the bread. Stir to combine.
Sprinkle an additional 1 Tbs of the powdered ranch dressing mix over the top and stir for a second time to coat everything evenly.
Add the breadcrumbs to the basket of the air fryer. Set for 350 degrees and fry for 3 minutes.
Remove the basket and toss the bread with a spoon, then replace the basket and fry for another 2 minutes.
Let the croutons cool and add to salad or soup. Enjoy!