Using a small sauce pan, add the butter to the pan over medium heat. Melt the butter and then add the flour, all the while whisking or using a spoon so that it does not brown. Allow the butter and flour to combine and bring to a soft small bubbling (still over medium heat).
As soon as the butter and flour mixture begin to bubble, REMOVE from the heat and add the milk (already just having brought to boil on the stovetop or in the mircrowave). Stir together with a wooden spoon until combined. Then add the salt, pepper and nutmeg. Combine and the place back on the stove top and bring to boil, stirring for one minute. The sauce should be thick, but very moveable.
Remove the pan from the heat and add the four egg yolks to the mixture one at a time and incorporate with a wire whisk.
With the grated cheese handy (reserve 1-2 tablespoons as it will be placed on top of the soufflé before baking), add 3 1/2 ounces to the sauce along with the chopped herbs. Mix until combined. (If you are making ahead, this is when you will put your sauce to the side and wait until you are about to serve to finish the rest of the recipe.)
Whisk the 5 egg whites with salt in a separate mixing bowl using a handmixer until creamy and airy, but do not over-mix them. About 2-4 minutes.
Add one large scoop of the whipped egg whites to the cheese sauce. Fold in gently. Gradually add the rest of the egg whites, folding gently to keep the airy goodness needed in the soufflé until all the whites are combined.
Pour into your prepared soufflé dish. Sprinkle the remaining 1-2 tablespoons of grated cheese on top and place in the oven (middle rack in the middle of the oven). Immediately upon placing the soufflé in the oven, turn the temperature down to 375 degrees. Cook for 25-30 minutes (DO NOT open the oven to check on the soufflé, no mater how tempted you are). At this point, the top should be nicely browned. Bake for 3-5 more minutes to make sure the soufflé is firm enough.
Remove from the oven and enjoy immediately with a vinagriette tossed green salad and a glass of wine.