Preheat the oven to 165 °C (325 °F).

Place onions, apple quarters, bacon, and sprigs of thyme in a roasting pan.

Remove the giblets from the turkey, rinse and pat it dry with paper towel, then place on top of the ingredients in the roasting pan. Using your hand, gently pull up the turkey skin from the meat and spread 60 mL (¼ cup) of butter under the skin. Generously season with salt and pepper.

Loosely cover the turkey with aluminum foil and cook in the oven for 3.5 hours, or until the internal temperature of the inner thigh reaches 82 °C (180 °F).

Remove the turkey and sprigs of thyme from the roasting pan and set the turkey aside.

In a large pan, melt 30 mL (2 tbsp.) of butter. Add the flour to make a roux and mix well.

Pour the remaining contents of the roasting pan into the pan and stir well until the mixture thickens. If the sauce becomes too thick, add water.

Mix the sauce with a hand blender until smooth, adjust the seasoning, and serve with the turkey.