Step 1: Preheat Oven and Prepare Water Bath
Preheat your oven to 350°F (175°C). Place a kitchen towel in the bottom of a large roasting pan (this prevents the flan mold from sliding). Set aside. Boil water in a kettle—you’ll need it for the water bath later.

Step 2: Make the Caramel
In a medium saucepan, combine 1 cup sugar and ¼ cup water. Cook over medium heat, stirring gently just until the sugar dissolves. Once dissolved, STOP stirring. Let the mixture cook undisturbed, swirling the pan occasionally, until it turns a deep amber color (like the color of an old penny), about 8-12 minutes. Watch carefully—it goes from perfect to burnt quickly! The caramel is ready when it’s a rich golden-amber color and smells nutty and caramelized, not burnt.

Step 3: Pour Caramel into Mold
Immediately and carefully pour the hot caramel into your flan mold or 9-inch round cake pan. Quickly tilt and swirl the pan to coat the bottom evenly and partially up the sides (the caramel will be VERY hot—use caution!). The caramel will harden as it cools—this is normal. Set aside to cool while you make the custard.

Step 4: Blend the Custard
In a large mixing bowl, whisk together the sweetened condensed milk, whole milk, eggs, vanilla extract, and salt. Whisk thoroughly for about 1-2 minutes until completely smooth and well combined. You want everything fully incorporated without any streaks of egg white showing.

Step 5: Strain the Custard
Pour the custard mixture through a fine-mesh strainer into another bowl or large measuring cup with a spout (this makes pouring easier). This crucial step removes any chalky bits from the eggs and ensures your flan will be impossibly smooth. Don’t skip it!

Step 6: Pour Custard Over Caramel
Carefully pour the strained custard mixture over the hardened caramel in your prepared pan. The caramel layer will stay at the bottom (it will become the top when you flip the flan later!). If any bubbles form on the surface, gently pop them with a spoon or use a kitchen torch.

Step 7: Create the Water Bath
Place the flan mold in the roasting pan (on top of the kitchen towel). Carefully pour hot water from your kettle into the roasting pan until it comes about halfway up the sides of the flan mold. Be very careful not to splash water into the custard! This water bath (bain-marie) ensures gentle, even cooking that prevents curdling.

Step 8: Cover and Bake
Cover the entire roasting pan loosely with aluminum foil to prevent a skin from forming on the flan. Carefully transfer to the preheated oven. Bake for 50-60 minutes, until the flan is set around the edges but still has a slight jiggle in the center (about the size of a quarter). It should look like barely-set Jell-O in the middle. Don’t overbake—the custard will continue cooking from residual heat.

Step 9: Cool and Chill
Carefully remove the roasting pan from the oven. Using oven mitts or tongs, remove the flan mold from the water bath and place on a wire rack. Let it cool to room temperature for about 1 hour. Once cooled, cover with plastic wrap and refrigerate for at least 4 hours, but preferably overnight. The flan needs this time to fully set and for flavors to develop.

Step 10: Unmold and Serve
When ready to serve, run a thin knife around the edges of the flan to loosen it from the mold. Place a large serving plate or platter (with a rim to catch the caramel sauce) upside down over the mold. Holding both the plate and mold firmly together, quickly flip them over. Give the mold a gentle shake—the flan should release onto the plate. Lift off the mold to reveal your gorgeous flan with caramel sauce cascading down the sides. If any caramel remains in the pan, drizzle it over the top. Slice and serve immediately, spooning extra caramel sauce over each slice!