Heat a large skillet over medium-low heat and add the bacon. Cook until it’s crispy and the fat is rendered. Remove the bacon and place it on a paper towel to drain any excess grease.
Season the chicken with salt and pepper. Cover with the rosemary. In the same skillet, over medium-high heat, add the chicken and cook until golden and crisp on both sides, about 5 to 6 minutes per side. Remove the chicken and let sit for a moment while you assemble the salad, then slice it.
Toss the greens with the watercress and the tomatoes. Top with the sliced chicken, the bacon and the avocado. Drizzle with the rosemary vinaigrette!
Whisk together the mustard, oil and vinegar. Whisk in the rosemary and a pinch of salt and pepper.