Preheat oven to 350 degrees fahrenheit.
In a saute pan over medium heat, begin to saute thinly sliced leeks until lightly golden brown (about 10 minutes).
While leeks are cooking, using two bowls, crack and divide egg yolk from white. Each bowl should have four egg whites. Add salt and pepper to each bowl, and beat the egg whites well until bubbles start to form (about 1 minute).
Lightly grease the two ramekins with cooking spray. Pour egg whites into individual ramekins. Gently mix-in the sauteed leeks and top each ramekin with two tablespoons shredded cheddar.
Bake for 20 minutes until the tops of the souffles are golden brown. Serve and enjoy.