Peel and thinly slice onions.Add butter and onion to a pan and sauté till they are translucent and beginning to brown, about 5 - 8 minutes.Add water and simmer for 25 minutes.Meanwhile, grate the cheese, and layer cheese and bread in an oven proof soup bowl (Individual bowls are better than one serving dish) Start with a thin layer of cheese, top with bread, another layer of cheese, and end with a layer of bread, reserving some cheese for later.When the soup is cooked, spoon onion and soup into soup bowls and top with remaining cheese.Place under grill for 5 - 10 minutes, keeping an eye on it till the cheese is browned. The dishes will be hot, so transfer carefully to a counter.Add one or both cheeses to the Thermomix (drop over running blades) speed 5, 10 - 15 seconds.Clean the bowl and set the cheese aside.Add the onions and butter to the Thermomix and blend 10 seconds speed 4.Sauté for 5 mins/100C/spoon speed.Add the water (remember to keep to the limits in the Thermomix, so 2000g for TM31)Cook reverse speed, Varoma/15 mins, without the MCMeanwhile in the soup dishes, start with a thin layer of cheese, top with bread, another layer of cheese, and end with a layer of bread, reserving some cheese for later.When the soup is cooked, spoon onion and soup into soup bowls and top with remaining cheese.Place under grill for 5 - 10 minutes, keeping an eye on it till the cheese is browned. The dishes will be hot, so transfer carefully to a counter.Enjoy