• Mix the spices with the minced garlic clove, mustard, dried herbs (not whole sprigs), butter, and olive oil.
• Rub the capon all over with the mixture. Gently loosen the skin over the breast and spread the spiced butter underneath.
• Place the thyme and rosemary sprigs, along with the two whole garlic cloves, inside the cavity.
• Cross the legs of the capon and tie them with kitchen twine. This helps the bird keep its shape while roasting. You can slip the legs through the opening near the tail, then cross and tie them securely.
• Place the sliced onion in a deep roasting dish or casserole dish and set the capon on top. You may skip the onion if you prefer.
• Roast at 300°F (150°C), allowing 45 minutes to 1 hour per 1kg (2.2 lb) of poultry. For a 3 kg (7 lb) capon, plan on about 3 hours of cooking time.
• Chef’s tip: Toward the end of cooking, lightly sprinkle a small pinch of salt over the entire bird. This helps achieve a beautifully golden skin. Use a light hand, just a pinch is enough.
• If you roasted the capon on a bed of sliced onions, lift it near the end of cooking and place it directly on an oven rack for the final minutes. This allows excess juices to drip away and helps the underside brown and crisp nicely.

Check for doneness

• The easiest way to check if the capon is cooked is to insert a skewer into the meat where the thigh meets the breast. The juices should run clear, with no trace of pink or blood.
• For a more precise method, and the one used by professionals, you can use a meat thermometer. Insert the probe into the thickest part of the capon and check that the internal temperature reads 165–180°F (75–82°C) for perfectly cooked, juicy meat.

Prepare the Side Dish

• Peel and wash the baby potatoes. Place them in a large pot and cover with water. Add 1/2 teaspoon salt and a large sprig of fresh thyme. Cook for about 20 minutes, until just tender.
• Drain the potatoes in a colander.
• Mix the Herbes de Provence with the olive oil and garlic powder. Toss the baby potatoes in this mixture until well coated. Arrange them on a lightly oiled baking dish and place in the oven 20 minutes before the capon is done. Roast until the potatoes are golden brown.
• If you prefer to use green beans, broccoli, or carrots, cut them into julienne strips and steam them, if possible. Then proceed in the same way as for the baby potatoes.

How to serve the capon

• Once the capon is cooked, loosely cover it with a sheet of aluminum foil and let it rest for about 10 minutes before serving. This allows the meat to relax, making it more tender and helping it retain its juices and flavor.
• Transfer the capon to a serving platter and remove the kitchen twine from the legs. Arrange the baby potatoes around the bird.
• Mix 1 tablespoon oyster sauce with 1 tablespoon broth. Using a pastry brush, lightly brush the capon with this mixture. Sprinkle with a few fresh thyme leaves.
• Spoon the slow cooked onions into a small sauce boat and serve alongside.
• Serve the capon immediately and enjoy.
• I hope this oven-roasted Christmas capon will inspire you to make it for Christmas, New Year's Eve or any other occasion.