Cut the onion into small cubes and sauté with 2 tablespoons of butter. As soon as the onions are glassy, add the flour and sauté. Deglaze with the cream.
Cut the gorgonzola into cubes and add to the cream and onions. Melt slowly at medium temperature. Stir occasionally, do not forget.
Meanwhile, cook the fresh tortellini and spread them in an ovenproof dish.
Spread the melted Gorgonzola sauce over the tortellini and mix. If necessary, season with some pepper or herbs from Provence.
Place the casserole dish in the oven at 180 - 200 C° for about 20 minutes. As soon as the casserole is slightly crispy/brown from above, it is ready.