In a small ramekin, whisk together the spicy mustard with lemon juice, salt, pepper and thyme.
Place the two chicken breasts in a bowl and pour the mustard over them. Using a spoon, coat the chicken breasts with the mustard. Place in the refrigerator to marinate 10 minutes then remove and bring to room temperature 15 minutes prior to cooking.
Preheat oven to 350 F. Prepare a baking sheet with parchment paper.
Next place Brussels sprouts in a medium bowl and toss with melted coconut oil, salt and pepper.
Transfer Brussels sprouts to the prepared baking sheets, spreading into an even layer.
Place marinated chicken breasts in a glass baking pan.
Place the chicken breasts in the oven baking at 350 F 10 minutes. After 10 minutes, place the Brussels sprouts in the oven. Cook both 15 minutes.
Remove from the oven and divide the meal into two servings, placing in individual meal prep containers.