Heat oil in a small nonstick pan over medium heat and add garlic. Saute, stirring constantly, until softened.
Add in the cubed bread and cook, stirring constantly, until golden, then set aside.
In a small bowl, mix together the egg, zucchini, cheese, salt, pepper, and water.
Pour into another nonstick pan then place over medium heat. Cook until the bottom of the omelet sets, lifting the edges occasionally to let the uncooked egg flow underneath. Flip the omelet over with a spatula and cook until firm, about 1 more minute.
Place croutons over half of the omelet, then using the spatula flip half of the omelet over the other half enclosing the croutons.