With the rack in the middle position, preheat the oven to 190 °C (375 °F). Line a high-sided baking sheet with parchment paper.
In a skillet, brown the bacon. Add the mushrooms and sauté until they have rendered their juices. Remove from the heat and add the tomatoes. Season with salt and pepper. Set aside.
On a cutting board, butterfly the chicken. To do this, place the chicken on its back, stick a knife in the centre and cut through the back bones. You can also ask your butcher to do it.
Place the chicken (or chickens) flat on the baking sheet. Cover with the butter and mustard. Sprinkle with the breadcrumbs and paprika. Season with salt and pepper.
Bake for about 50 minutes for small chickens and between 1 hour and 1 hour and 15 minutes for a large chicken. Add the mushroom mixture around the chicken and cook for an additional 15 minutes or until a meat thermometer reads 82 °C (180 °F).
Cut the chicken into pieces and serve with the mushrooms and rice or mashed potatoes.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.