Pre-heat the oven to 450 degrees F. Wash, pat dry, and season chicken thighs with salt and pepper.
Heat olive oil in a skillet over medium and place chicken into the pan, skin side down. Cook each for 7-8 minutes, or until the skin is brown.
Cut garlic cloves in half long ways to make 20 pieces of garlic. Combine in a bowl with 1/2 cup chicken broth and chopped leeks.
When the chicken is finished, place chicken pieces skin side up into a casserole dish. With the oil remaining in the skillet, turn the stove heat off and add the garlic and leek mixture to the pan. Stir to coat, scraping the edges of the pan.
Pour the garlic and leek mixture evenly over the chicken thighs. Bake for 28-30 minutes, or until juices run clear.
To make the mashed potatoes, boil the potatoes, drain them, mash them up, and add butter, kale greens, chicken broth, salt, and pepper to taste.
When the chicken is finished baking, place a scoop of mashed potatoes on each plate and top it with a chicken thigh. Garnish with leek and garlic pieces and the juice from the baking dish.