Preheat the oven to 375 degrees. Lightly grease with olive oil or avocado oil a baking dish. Set to the side.
In a small bowl, or liquid measuring cup, mix together the honey mustard ingredients.
Place the chicken breast in the baking dish. Season both sides with salt, pepper, onion, and garlic powder. Pour half of the honey mustard over the top of the chicken breasts. Evenly spread a layer of the sauce over the chicken.
Bake the chicken in the oven for 25 minutes, or until the temperature reaches 165 degrees.
Meanwhile, using a large skillet, heat the oil over medium heat. Once the oil is warm add half of the kale. Season with a pinch of salt. Stir occasionally. When the kale has reduced some what add the remaining kale. Add the lemon zest and half of the lemon juice. Stir and mix util the kale has wilted.
Once the chicken has cooked, carefully remove the baking dish from the oven. Serve the chicken and kale immediately and enjoy!