Start by buttering the mold and sprinkling with cheese. I chose to use Parmesan cheese because it grated finer than Gruyere. Preheat oven to 400 degrees.

The foil wrap: This will make sure that your souffle will not spill over and will keep a high mold.

Tear a long enough piece of foil so that it is long enough to wrap around your mold. Fold in half length-wise and butter one side. The buttered side will be the "inside" of the mold. Wrap the foil around the mold. If your mold has little handles like mine does, cut small slits so the foil can fit. Secure lose top ends with paper clips.

Melt the 3Tb of butter in a sauce pan and stir in the flour with a spatula, cooking over medium heat until the butter and flour foam together for about 2 minutes without browning.

Remove from heat. When mixture has stopped bubbling, pour in all of the boiling milk at once and beat vigorously with a whisk until well blended.

Remove from heat, take the egg yolks and beat 1 egg yolk into your white cream mixture one at a time until well incorporated.

Now for the egg whites. In a clean, dry mixing bowl, begin to beat your egg whites with a whisk attachment on low speed. You will see that the egg whites will "break up" and begin to have a foamy consistency.

As the egg whites are foaming, increase the speed gradually and add cream of tartar and a pinch of salt. Increase the speed to fast and continue to beat for a few more minutes.

Do not leave your egg whites! Continue checking them. What you want to see are "traces" on the surface. The egg whites should also have a glossy white sheen and be able to be stiff and firm when holding with a whisk.

Once the egg whites are done, don't let them sit for long. Take a large spoonful and stir it into the cream mixture to lighten it.

Stir in all but about 1Tbl of the grated cheese into the cream mixture.

There is a technique with folding the rest of the egg whites. Take one large spoonful of the egg whites and using your spatula, cut down the middle and draw the spatula under, while scraping the side of the pan and turning the pan with the other hand. Basically, you folding under and to the side.

Continue with the rest of the egg whites. Be careful not to over fold. It's OK if there are white streaks leftover. Now your mixture is ready! Carefully pour your mixture into the prepared mold. It should be about ¾ high. Tap the mild carefully to even it out and top with remaining Tb of cheese.

Place on middle-back rack of pre-heated 400 degree oven.Once in, immediately turn down to 375 degrees.

Bake for exactly 30 minutes and DO NOT, I repeat, DO NOT open the oven door ever during that 30 minutes!

The souffle will have puffed up a few inches over the mold and will be a gorgeous golden brown on top. Insert a tester, if it comes out clean, it's done.

To serve: Use 2 spoons and lightly puncture the top of the souffle. Don't scoop from the bottom, that will deflate it, just spoon vertically.