Heat the oil and season the chicken fillet with salt and pepper. Fry in the oil and add onion cubes, then broccoli, mushrooms and peppers and fry for several minutes. The meat should be well done, the vegetables at least firm to the bite. Add tomato paste and sweat with it.
Add ajvar and deglaze with cream. Fill up with a little water and season again with salt and pepper. Possibly season with more ajvar. The sauce shouldn`t be too runny!
Brush the gratin dish with oil and add a layer of pasta. Spread half of the cheese on top. Pour the sauce on top and finish with a second layer of pasta and grated cheese.
Put in the oven at about 150 degrees and bake for about 10-15 minutes until the cheese has melted.