Preheat your oven to 350 degrees. As your oven preheats, gently mix the evaporated milk, condensed milk, egg yolks, and vanilla extract in a blender.
Meanwhile, in an 8 inch circular cake pan, pour 1 cup of sugar and heat it on a medium-low setting; melting it until you get a light caramel color.
After reaching a light caramel color, set the pan aside for a minute, allowing it to harden a bit. Then, pour the mixture from the blender onto the caramelized sugar and cover the cake pan tightly with aluminum foil.
Next, gently place the tightly sealed cake pan into a bigger pan and then slowly pour water around the pan; this is known as the "bain-marie", or "water bath." After pouring water around the pan, place it onto the center of the oven rack and bake it at 350 degrees for one hour.
After an hour, take it out and let it cool for about 5 to 10 minutes. Then, refrigerate it for at least 4 hours
To serve your flan, run a knife around the edges, place your serving platter on top of it, quickly turn it over and your flan is served! (Of course you may garnish it with whatever you'd like; however, it doesn't need a single thing!)