Place the sugar in a heavy-bottomed saucepan over medium heat. Stir gently until it melts and turns a deep golden amber color, about 8 to 10 minutes. Carefully pour the hot caramel into a flan mold or round baking dish, tilting to coat the bottom evenly. Set aside to cool while you prepare the custard. Preheat the oven to 350°F (175°C).

Add the sweetened condensed milk, evaporated milk, whole milk, eggs, optional egg yolks, vanilla extract, orange zest, orange juice, water, and cornstarch to a blender. Blend for about 1 minute until smooth, avoiding overblending. If using cream cheese, blend it in until completely smooth.

Slowly pour the custard mixture over the cooled caramel. Place the flan mold inside a large roasting pan lined with a folded kitchen towel. Carefully pour boiling water into the roasting pan until it reaches halfway up the sides of the flan mold.

Bake for 45 to 60 minutes, or until the edges are set and the center still has a slight jiggle. A knife inserted near the center should come out mostly clean.

Remove the flan from the water bath and allow it to cool completely at room temperature. Refrigerate for at least 4 hours, or overnight for the smoothest texture and richest caramel flavor.

Run a thin knife around the edge of the mold to loosen the flan. Place a serving plate over the mold and carefully invert it. Let the caramel sauce flow over the custard, then serve chilled with whipped cream, fresh berries, mint leaves, or extra orange zest if desired.