Step 1Place 1 cup sugar in saucepan over medium heat. Swirl pan constantly until sugar melts and caramelizes, turning a golden brown, 10 minutes. Pour into 10-inch round cake pan. Set aside.
Step 2In blender, combine eggs, evaporated milk, whole milk, remaining sugar and vanilla. Blend until well combined.
Step 3Slowly pour egg mixture into pan. Cover with foil and place in baking dish. Add hot water to come halfway up sides of cake pan. Bake at 350 degrees until knife inserted in flan comes out clean, 45 to 55 minutes.
Step 4Refrigerate until just before serving, 4 to 6 hours. Invert onto platter and serve.