Pre-heat the oven to 325 F
Make the caramel by adding the sugar to a pot without touching the edges, and pour over the water. Do not stir it or move the pot and remain close by to watch it
Allow it to come to a boil over medium heat and stand by until it caramalizes by seeing some change in color. This should take about 10 minutes. You can then swirl the pan and wait until it turns a dark orange
Remove from the heat and pour it into your cake pan ensuring you cover the whole base by moving the pan around (carefully as the pan will get hot)
Next prepare the custard by blending together the eggs, condensed milk and whole milk. If your blender is small do it in 2 batches (half the ingredients for each batch)
Pour the custard on top of the caramel (which has solidified by now) all the way to the top
Place the pan in a larger baking dish and add boiling water half way up the pan's edge
Bake in the oven for 45-50 minutes. Check the custard at around 38 minutes by jiggling it slightly. If it ripples like water, it's not ready. You need it to jiggle like set jelly. You can also insert a knife in the middle. It should come out mostly clean with a few streaks (not with little clumps).
Take it out and allow it to cool at room temperature inside the water bath.
Place it in the fridge for at least 4 hours or overnight
When ready to serve, run a knife along the edge pressing against the edge of the pan to avoid cutting into the custard
Place a plate with a raised edge on top of the pan and flip!