Dice the tomatoes and peppers. Cut the spring onions into rings. Divide the vegetables into 3 small molds, season with salt and pepper.
Wash the chicken breast fillets, season with salt and pepper on both sides and cut into a fan-like shape on one side. Cut the mozzarella into slices. Brush the fillets with pesto and put a slice of mozzarella in each cut fan.
Place the chicken breast on the vegetables and bake in the preheated oven at 180 ° C top / bottom heat for about 30 minutes. Finally switch on the grill for 5 minutes.