Heat oil in a pan, add garlic and onions (if using) and cook till onions turn translucent.
Next add the mushrooms and green pepper. Cook till both the veggies are tender. Season with Salt and pepper. Set aside.
Preheat the oven to 400°F.
Slice the bread in half and scoop out some of the crumbs from inside. Place the mushroom mixture on the bread and top with grated cheese. Place it on a baking sheet and bake for 5~8 minutes or until the cheese is melted.
Remove from the oven and drizzle with ketchup and sprinkle with the chives. Serve and enjoy!!