Preheat oven to 425°. Place chicken on one side of a rimmed baking sheet lined with foil and sprayed with cooking spray. Drizzle with 1 tbsp oil and sprinkle with ⅛ tsp of salt. Roast for 10 minutes.
Place sliced lemons on other side of baking sheet. If you need to use a second baking sheet to fit all the lemons you can do that, as well. Place back in oven and roast for another 10 minutes. Open oven and flip the lemons and roast for 10 more minutes or until the inside temp of the chicken reads 165°.
Meanwhile, in a small pot, add your broth and quinoa. Follow package directions for cooking.
If you are cooking your broccoli, using fresh broccoli, chop up into bite sized pieces. Add your chopped broccoli to a steamer basket. Add enough water to a pot to come up to about 1 inch. Bring to a boil over medium heat. When water is boiling, carefully add your steamer basket with the broccoli into the pot and cover with lid and steam for 5 minutes. Once done, remove from heat and place in a bowl and keep warm. Or, to cut corners toss a bag of broccoli into the microwave.
In a large bowl make your dressing using the vinegar, mustard, remaining 3 tbsp oil, salt, and pepper. Shred chicken using 2 forks and add chicken, lemon, broccoli, spinach, nuts, and cranberries to the dressing and toss to combine. Drizzle with more dressing before serving; if desired.
To plate, spoon your quinoa out into a dish and top with the chicken mixture.