Season the chicken breast with half of the sea salt, black pepper, and one teaspoon of olive oil.
Preheat a grill or grill pan over medium-high heat and cook the chicken for 6-7 minutes per side until the internal temperature reaches 165 degrees Fahrenheit.
While the chicken cooks, cut the whole-grain bread into small cubes and mince the garlic clove.
Toss the bread cubes with one teaspoon of olive oil and the minced garlic, then toast in a pan over medium heat until golden and crunchy.
In a small bowl, whisk together the Greek yogurt, lemon juice, Dijon mustard, the remaining olive oil, and the remaining salt and pepper to create the dressing.
Chop the romaine lettuce and place it in a large bowl, then toss thoroughly with the prepared yogurt dressing.
Slice the grilled chicken into strips and arrange them over the salad greens.
Garnish the salad with the garlic croutons and a sprinkle of parmesan cheese before serving.