Steps
1. Heat olive oil in a skillet over medium heat.
2. Add the sliced onions and cook until caramelized, about 5 minutes.
3. Add the diced chicken and cook until browned and cooked through, about 7 minutes.
4. Stir in the sliced mushrooms and cook until tender, about 3-4 minutes.
5. Season with salt and pepper to taste.
6. Toast the slice of bread until golden brown.
7. Top the toasted bread with the chicken and mushroom mixture.
8. Add fresh tomato slices on top.
9. Garnish with fresh basil leaves and serve warm.