Heat the oil and butter in a large skillet over low to medium heat.
Add the onions and cook them down slowly until starting to brown, about 25 minutes.
Add the garlic, dried thyme, salt and pepper. Cook until fragrant, one minute.
Add red wine and cook down until the liquid is gone.
Add the flour and stir. Brown for 2 minutes.
Add the beef stock. Cook down until thickened, about 5 minutes.
Turn the oven broiler on high.
Line a baking sheet with aluminum foil and spread the sliced baguette pieces out.
Broil the bread until it just starts to turn golden. Pull from the oven.
Carefully divide the cooked down onions over the bread slices. Sprinkle with shredded cheese
Broil until the cheese has melted, about 1 minute.
Serve immediately. Enjoy!