Creme Brulee Recipe Confusion

I am going to attempt to make creme brulee for my parents anniversary and I need help. I have researched a lot of recipes and am more confused now than ever. All the recipies have the same ingredients, egg yolks, heavy cream, sugar, and vanilla...but the quantities all vary for the same number of servings. Do I use 8 egg yolks to a quart of cream? 11? 6? How does the varying quantity of ingredients change the outcome?