Wash the chicken fillets, pat dry and season with salt. In a large pan in a little oil, sear for about 2 minutes on each side. Cut the broccoli into bite-sized pieces and place in a large baking dish with the chicken fillets and add a little pepper. Cook in the oven at 200 ° C for about 10 minutes.
In the meantime, core the chilli pepper and cut into small rings. Finely grate the cheddar. Heat the cream in a saucepan and melt the grated cheddar in it. Add the chopped chilli and season with salt and pepper. Depending on how spicy you like it, you can cut a jalapeño into slices and add it.
Pour the sauce into the baking dish and spread the gratin cheese over it. Bake everything together for another 10 minutes.