Pat the chicken breast dry. In a small bowl, combine the juice from half a lemon, one minced garlic clove, and a teaspoon of olive oil to create the marinade.
Marinate the chicken breast for at least 15 minutes while you prepare the other components.
Preheat your oven to 425°F. Cut the broccoli into florets, toss with a drizzle of olive oil, salt, and pepper, and spread evenly on a baking sheet. Roast in the oven for approximately 15 minutes until tender and slightly crispy.
Meanwhile, peel and dice the potato. Boil in lightly salted water until tender, about 15-20 minutes.
Drain the potatoes and return to the pot. Add 1/4 cup of skim milk and 1 teaspoon of butter, then mash until smooth and creamy. Season with salt and pepper to taste.
While the vegetables roast and potatoes mash, heat a skillet over medium-high heat and add the marinated chicken breast. Sear on each side for about 4-5 minutes until golden brown and fully cooked (internal temperature should reach 165°F).
Plate the pan-seared chicken next to a serving of creamy mashed potatoes and roasted broccoli. Squeeze any remaining lemon juice over the chicken for an extra burst of flavor and serve immediately.