Use a peeler and pull slices from the zucchini (see tip). Fry the minced chicken in some olive oil. Once cooked, mix in the tomato paste. Season with oregano, thyme, pepper and salt.
Take another pan, pour in the cream and add the gruyere. Note! Keep some gruyere aside for finishing. Heat gently so that the gruyere melts and you get a thick sauce.
Take a baking dish and place several slices of zucchini in it in a tile fashion. Spoon some minced meat on top and a little cheese sauce from the pan. Be careful to be sparing because there will be a few more layers to follow.
Put another layer of zucchini on top and again some minced meat and cheese sauce. Repeat until everything is gone, finishing with minced meat and on top of that the remaining cheese sauce. Sprinkle some extra gruyere on top and put in the oven at 180 °C for 20 minutes.

Tip: Slicing zucchini
This is easiest with a peeler. If you hit the seeds, turn the zucchini over and start again. The middle piece with the seed section contains a lot of liquid and can be used, for example, in a soup.

Tip: Minced meat
I like to choose minced chicken; it is particularly tasty and less environmentally damaging than, say, beef. I discussed this in more detail in my book I Like to Eat 2.