At least 30 minutes (but no more than 1 hour) before you plan to start cooking the chicken, take it out of the refrigerator and let it come up to room temperature.

Preheat oven to 425°F with convection (450° without convection) // 220° - 230°C.

In a small bowl, combine softened butter with lavender, rosemary, sage, thyme, tarragon and half of the salt and pepper. Mix until thoroughly incorporated. (This is compound butter.)

Pat chicken completely dry with paper towels.

Very gently, separate the skin from the breast meat by sliding a couple fingers between the skin and the flesh to pull the membrane away from the meat. (*See note) Place about 3/4 of the compound butter on breast meat, spreading over both sides of the breast.

Use remaining compound butter to spread over the outside of the chicken. Sprinkle remaining salt and pepper over the chicken.

Add sliced lemon to the cavity of the bird and use butcher's twine to tie the legs together. Tuck the wing tips under the back of the chicken.

Place the 4 rounds of onion in the bottom of a 10 - 12 in. cast iron skillet (or oven-proof sauté pan). Place the trussed chicken on top of the onions.

Roast the chicken for 20 minutes, then add vegetables. Scatter them around the chicken and return the pan to the oven for an additional 40 - 45 minutes.

Remove the chicken from the oven and let it rest for 10 minutes before carving.