Preheat the oven to 220 C (425 F). Flatten the chicken breasts slightly by pounding them with a rolling pin until the whole breast is of the same thickness.
In a small bow, mix together all the dry ingredients, mustard, and olive oil until a paste forms.
Line a baking sheet with parchment paper, place chicken breasts on parchment paper, and spread the spice and oil paste evenly all over the chicken breasts, bottom and top.
Bake the chicken for 18-20 minutes, until cooked through. For the final 1-2 minutes of cooking, if chicken hasn't browned, use the broil function of your oven to give it a touch of color. Watch carefully!
Allow chicken to rest for a few minutes before serving.