Place sugar into a 9-inch ring mold and cook over medium-high heat, stirring constantly, until sugar melts and turns golden, about 10 minutes. Watch carefully for syrup to start to change color as it burns easily. Let caramel cool and harden, about 20 minutes.
Combine sweetened condensed milk, evaporated milk, eggs, cream cheese, and vanilla extract in a blender; blend until smooth, about 1 minute. Pour mixture over the hard caramel syrup in the tin and cover with aluminum foil. Pierce foil in the center hole of the ring with a knife; peel back foil, leaving hole uncovered for steam to circulate.
Place a metal rack inside a large pot over medium heat. Add water to almost reach the rack; bring to a boil. Place the mold on the rack, cover the pot, and steam until flan is set and firm, about 45 minutes. Unmold flan onto a serving plate and let cool before serving.