In a large frying pan, melt the butter and cook the onions for 5 minutes. Add the consommé and reduce fully (10 minutes).
Mix the softened butter with the onion powder and pepper.
Butter 4 slices of bread. Turn them over (butter side down).
Spread with mustard, add the hot onions, chicken and cheese. Close with the remaining slices.
Butter the top and grill 2–3 minutes per side, until golden and melted.
*Recipe courtesy of Isabelle Huot, Doctor of Nutrition