Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
Dice the sweet potatoes into one-inch cubes and chop the broccoli into bite-sized florets.
In a small bowl, whisk together the extra virgin olive oil, fresh lemon juice, honey, minced garlic, oregano, sea salt, and black pepper.
Place the chicken breasts, sweet potatoes, and broccoli on the sheet pan, then drizzle with half of the lemon-herb dressing.
Toss everything well to ensure an even coating and spread the ingredients into a single layer.
Roast for 25 to 30 minutes until the chicken is cooked through and the sweet potatoes are tender and caramelized.
Slice the avocados and arrange them over the roasted chicken and vegetables.
Sprinkle with walnuts and drizzle the remaining dressing over the entire dish before serving.