Thinly slice the onion along the grain, place it in a microwave-safe container, cover with plastic wrap, and heat in a 600W microwave for 3 1/2 minutes.

Melt the butter in a pot, add the onions from step 1, and sauté over low heat until caramelized (about 20 minutes).

Place cheese on the French bread slices and toast in an oven toaster until lightly browned.

Add water and consommé to the onions, season with salt and pepper, and bring to a boil. Serve the soup in bowls and top with the toasted bread.