Whip 8 egg whites in a standing mixer with the whisk attachment over medium- high speed. If the egg whites reach stiff peaks before the sugar and water mixture is ready, simply turn down the mixture to medium speed until it's ready.
Stir the sugar and water together in a small saucepan and turn on medium-high heat. Insert a thermometer into the sugar and water mixture and let it reach 240 degrees. Remove it from the heat immediately and slowly pour in the simple syrup in between the whisk and the side of the bowl so it doesn't stick to the bowl. You don't want the sugar/water mixture to go above 250 before adding it to the egg whites.
On medium-high speed and whip until the bottom of the outside of the bowl is cool to the touch, about 15 minutes. You can place ice packs around the bowl to cool the bowl down faster.
Now add in the 4 sticks of butter (in chunks) until they are incorporated. The mixture will deflate and almost curdle or look soupy, but DON'T WORRY, this is normal. Just keep whipping until it comes back together.