Preheat oven. Adjust oven rack to center position and preheat oven to 375 degrees Line a large, rimmed baking sheet with parchment paper.
Cube or tear bread. Either cut bread into ¾ inch-cubes with a knife or tear bread into small chunks by hand. Make sure the croutons are uniform in size so they bake evenly.
Toss with oil and seasonings. Place cubed bread in a large bowl. Drizzle bread with oil. Toss to coat. Sprinkle with parmesan, garlic, seasoning, ½ teaspoon kosher salt and ¼ teaspoon black pepper. Gently toss to evenly coat.
Spread croutons out on a rimmed baking sheet. Transfer the bread cubes onto the prepared baking sheet. Make sure the croutons are spread out in a single, even layer.
Bake. Bake the croutons, tossing once halfway through baking, for 15-20 minutes, or until the croutons are golden brown and crispy. Remove from oven and season with salt and more parmesan if desired. Allow the croutons to cool slightly on the pan. Use immediately, or allow transfer to a plate and allow to cool completely before storing in a zip-closure bag.
Do NOT overcrowd the baking sheet. You want the croutons in a single layer with some space left between each cube of bread.
Baking time will vary depending on the size of your croutons and how moist your bread is.
To Store Croutons: Croutons should be stored in a zip-closure bag at room temperature. To keep croutons fresh, remove as much air as possible from the bag before sealing. Croutons will keep for up to 2 weeks.
Croutons can be frozen for up to 4 to 6 weeks. To use frozen croutons, thaw them on a paper towel at room temperature for 1 hour. Heat on a baking sheet at 250 degrees Fahrenheit until crisp.