Preheat oven to 325°F (165°C). Prepare a large roasting pan with 1 inch of hot water for the water bath.

Make the caramel: In a small saucepan over medium heat, combine 1 cup sugar with 3 tablespoons water. Swirl the pan gently without stirring until sugar dissolves and turns deep amber, about 8-10 minutes. Immediately pour caramel into 8 ramekins, tilting to coat the bottoms evenly. Set aside to cool.

In a large mixing bowl, whisk together 6 eggs and 4 egg yolks until well combined but not frothy.

In a medium saucepan, warm 1 can (14 oz) sweetened condensed milk, 2 cups whole milk, and 1/2 cup heavy cream over medium-low heat until steaming but not boiling. Remove from heat.

Add 2 teaspoons vanilla extract and 1 teaspoon instant coffee dissolved in 1 tablespoon hot water to the milk mixture. Stir well.

Slowly pour the warm milk mixture into the eggs while whisking constantly to prevent curdling. Strain the mixture through a fine-mesh sieve into a large measuring cup.

Divide the custard mixture evenly among the prepared ramekins. Skim off any bubbles from the surface.

Place ramekins in the roasting pan with the water bath. Carefully transfer to the oven.

Bake for 45-50 minutes until the custards are set but still slightly jiggly in the center. A knife inserted near the edge should come out clean.

Remove from water bath and cool to room temperature. Cover each ramekin with plastic wrap and refrigerate for at least 4 hours or overnight.

To serve, run a thin knife around the edge of each flan. Invert onto individual serving plates, allowing the caramel to flow over the custard. Serve chilled.