Sauté the Mushroom (1 cup) in butter or oil. Set aside.
Line up two slices of Emmental Cheese (2 cup) and sprinkle each piece with 1/2 cup of Rye Bread (4 slice).
Top each slice of bread with the leaves from one spring of Fresh Thyme (2 sprig).
Add 1/4 cup of Caramelized Onions (1/2 cup) to each slice of bread.
Add 1/4 cup of sautéed mushrooms to each slice of bread.
Finish by sprinkling 1 tablespoon of Salt (to taste) and Grated Parmesan Cheese (2 tablespoon) over each slice of bread. Top each mixture with another slice of bread to make a sandwich.
For each sandwich, heat a saucepan over medium heat and add 1 tablespoon of Butter (2 tablespoon). Once butter has melted, add sandwich to the pan and cook until golden brown on both sides.
Remove the sandwich from the pan and add 1/2 cup of emmental to the pan.
Allow the emmental to melt and then return the sandwich to the pan directly over the emmental
Once the crust is formed and the bread is slightly browned, flip the sandwich.
Sprinkle 1 tablespoon of Grated Parmesan Cheese (2 tablespoon) and 1 tablespoon of grated Emmental Cheese (2 tablespoon) around the crust of each sandwich.
Allow remaining cheese to heat and form a crust. Then flip sandwich onto plate, cut in half and serve!