Preheat oven to 350 degrees F.
Flan must be baked in a bain-marie, or hot water bath. Prepare a larger pan big enough to hold 6-8 ramekins, a 1 1/2 quart casserole dish or an 8-9" cake pan. Place the pan with the empty ramekins or casserole in the oven to preheat while preparing the caramel.
In a small nonstick saucepan, warm the granulated sugar over medium heat. Shake and swirl the pan occasionally to distribute the sugar until it dissolves and starts to color.
Once almost all the sugar is melted, turn the heat down to medium-low and continue swirling the pan until the caramel turns dark golden brown. You can slow the cooking process by lifting the pan over the heating element (4-6 inches) if you are worried it's browning too quickly. You don't want it to burn because it will have a very bitter taste.
Once browned, divide the caramel between the preheated ramekins or pan. Set aside to cool while preparing the custard.
Heat a kettle of water to boiling and set aside.
Place all remaining ingredients (except pepitas) into a blender and process on high for at least one minute. Divide the custard between the ramekins. Place the pan holding all the ramekins in the preheated oven. Carefully pour hot water into the pan to about 1 inch in depth. Close the oven and bake for 60 minutes or until the custard is set.
Cool completely, then cover and refrigerate until ready to serve. The flan should be fully chilled before serving.
To serve, slide a small sharp knife around the edge of the dish. Shake the ramekin back and forth until you hear the custard pulling away from the sides of the dish. Invert the flan onto a plate to serve. Garnish with pepitas if desired.