1. Fill a roasting pan with 2 inches of water. Transfer to oven; preheat to 325 degrees. Prepare an ice-water bath; set aside.

2. Cook sugar in a small saucepan over medium-high heat, stirring constantly and washing down sides with a wet pastry brush to prevent crystals from forming, until sugar dissolves. Continue cooking until sugar turns a deep caramel color. Immediately dip bottom of pan in ice-water bath, then pour caramel into an 8-inch round cake pan.

3. Blend condensed milk, milk, and eggs in a blender until smooth. Pour into cake pan. Transfer to roasting pan, placing it in the water. Bake flan until just set and golden brown on top, about 1 hour.

4. Transfer flan to a wire rack to cool. Chill 6 hours or preferably overnight.

5. Just before serving, run a knife around edge of flan. Set a serving plate over pan; invert. Spoon sauce from pan over flan.