Updated Jun 18, 2019Chatelaine
1. Preheat oven to 350F. Place an 8-in. round baking dish in a large roasting pan. Boil a kettle of water.
2. Stir sugar with cold water in a medium saucepan over medium-high. Cover and bring to a boil, without stirring, 3 to 5 min. Remove lid and let mixture boil until it turns amber, 5 to 7 min.
3. Immediately pour hot caramel into the bottom of the baking dish. Quickly swirl to coat bottom evenly. Set aside to let caramel harden.
4. Beat egg yolks, using a fork, in a medium bowl. (Avoid beating too hard and creating frothy bubbles.) Gradually beat in sweetened condensed milk. Stir in evaporated milk and vanilla. Strain mixture through a fine-mesh sieve over caramel in baking pan.
5. Pour hot water from the kettle into the roasting pan until it comes one-third up the sides of the dish (be careful not to splash water into the custard). Bake until the edge is set but the centre jiggles slightly when gently shaken, 30 to 35 min. Transfer baking dish to a wire rack to cool completely, preferably overnight.
6. To serve, run a paring knife around the edge of baking dish to loosen the custard. Set bottom of dish in warm water for 1 min to loosen caramel. Hold an inverted serving plate over dish, then quickly flip plate and dish together to release an onto plate.
To make ahead, cover cooled flan with plastic wrap and refrigerate up to 3 days.