Add ½ cup (90 g) sugar, 3 tablespoons (45 ml) cold water, and 1 teaspoon lemon juice to a small saucepan. Cook over medium heat until the sugar dissolves and turns into a deep golden caramel. Carefully pour the caramel into a glass mold, swirling to coat the base, then set aside to cool and harden.
In a large bowl, beat 5.3 oz (150 g) cream cheese with ¼ cup (50 g) sugar until smooth and creamy. Add 3 large eggs, one at a time, beating well after each addition. Pour in 1 cup (250 ml) milk and ⅓ cup (100 ml) heavy cream, then mix until smooth. Strain the custard through a sieve into the caramel-coated mold.
In a separate bowl, beat 1 large egg with a hand mixer on medium-low speed for about 1 minute. Add 2½ tablespoons (30 g) sugar and beat to combine about 4 minutes, until stiff peaks form. Sift in ¼ cup (30 g) flour and gently fold until fully incorporated.
Pour the cake batter over the custard. Place the mold in a large baking tray filled with hot water and bake in a preheated oven at 320°F convection / 160°C fan for 20 minutes. Remove the tray, cover the mold with foil, and bake again at 300°F convection / 150°C fan for 30 minutes.
Remove from the oven, lift the mold out of the water bath, and let it cool to room temperature. Refrigerate for at least 4 hours or overnight. Run a knife around the edges, place a plate on top, flip carefully, lift off the mold, then slice and serve.
Notes
Watch the Caramel Carefully: I like to remove it from the heat as soon as it turns deep golden because caramel can burn quickly.Strain the Custard: I always strain the mixture before baking to remove bubbles and keep the flan silky smooth.Beat the Cake Mixture Well: Whipping the egg mixture to stiff peaks helps create the light sponge layer.Chill before Unmolding: I prefer letting the flan chill overnight so it slices cleanly and the caramel settles beautifully over the dessert.