In a medium bowl, combine the stone ground mustard, dijon mustard, honey, and 1 tablespoon of olive oil.
Add remaining tablespoon of olive oil to a large, oven-safe skillet such as a cast-iron skillet.
Add onions and saute for about 3 minutes, until the onions are soft and almost translucent. Add garlic and saute for 1-2 additional minutes.
Add chicken to the pan and brown the chicken on all sides for about 2-3 minutes.
Turn chicken so the skin side is up, then pour the mustard mixture over the chicken to coat well.
Sprinkle basil leaves on and around the chicken.
Cover chicken with foil and bake at 375 degrees for 40-50 minutes, until the chicken is fully cooked through. Halfway through, baste chicken with the mustard sauce.
Notes
Chicken: The cook time for this recipe is for bone-in, skin-on chicken thighs.Basil: You can substitute the basil out and replace with any of your favorite green herbs (sage, rosemary, thyme).