Heat olive oil in a large skillet. Add garlic to the skillet, and cook, stirring frequently, until fragrant, about 1 minute. Stir in kale until bright green and wilted, about 3-4 minutes; set aside.
Preheat a waffle iron to medium-high heat. Lightly oil the top and bottom of the waffle iron or coat with nonstick spray.
Working in batches, place bread slices into the waffle iron. Top with kale, avocado, mozzarella, pesto and remaining bread slices.
Close gently and cook until golden brown and crisp, about 3-4 minutes.