Cut sweet pumpkin, chicken breast, and tofu into bite-sized pieces.
Steam the sweet pumpkin in a steamer for 10 minutes until soft.
Add olive oil to a pan and cook the chicken breast.
Place the cooked chicken breast, steamed sweet pumpkin, and tofu in a gratin baking dish.
Add tomato sauce or milk and cheese, then mix well.
Bake in a preheated oven at 180°C (356°F) for 15 minutes.
When the cheese is golden and bubbling, remove from the oven to finish.