Preheat the Oven: Preheat your oven to 350°F (175°C) and boil a kettle of water for the water bath.
Make the Caramel: In a small saucepan, combine the sugar and water. Cook over medium-high heat until the sugar dissolves and turns a rich, golden brown. Do not stir with a spoon; simply swirl the pan gently.
Coat the Ramekins: Immediately pour the hot caramel evenly into the bottom of your ramekins. Pour Just enough to coat the bottom. Set aside (the caramel will harden, which is expected).
Mix the Custard: In a large bowl, gently whisk the eggs, whole milk, sweetened condensed milk, and vanilla bean paste until completely smooth. Whisk gently to keep incorporated air bubbles to a minimum.
Strain the Mixture: Pour the custard base through a fine-mesh strainer into a pouring vessel. Discard any egg solids left in the strainer.
Fill and Cover: Pour the strained custard into the ramekins over the hardened caramel. Cover each ramekin tightly with aluminum foil.
Create the Water Bath: Place the covered ramekins into a large, deep baking pan. Carefully pour boiling water into the pan until the water reaches halfway up the sides of the ramekins.
Bake: Carefully transfer the pan to the oven and bake at 350°F for 50-60 minutes, or until the edges are set but the center still has a slight jiggle.
Chill and Serve: Remove the ramekins from the water bath and allow them to cool to room temperature. Transfer to the refrigerator for at least 4 hours (or overnight). To serve, run a thin knife around the inside edge of the ramekin, place a serving plate upside down on top, and quickly flip to invert the flan. Enjoy!