If you don't have an air fryer, you can also cook these on the stovetop or in the oven. Stovetop: Heat a little oil in a skillet on a medium high heat. Once add hot the croutons. Stir every minute or til crispy, about 5 to 7 minutes. Oven: Place the croutons on a lined baking sheet and bake in a preheated oven at 375F for 15 to 20 minutes, flipping half way.