This goes by a multitude of names. Flan, flan de leche, banh caramel, creme caramel, caramel custard, custard caramel (potato potato), custard pudding, lechetin. This version is gelatin based, it's a no steam, no bake recipe. It's still tedious but I consider it much less fussy than giving it a water bath.
The flan is fairly soft set, so if you'd like it firmer, reduce the milk by 1/4 cup.
Use any combination of milk (including different milk-fats), evaporated milk, half&half, or cream. You can also sub out one egg for two egg yolks. Obviously, the fattier your milk and the more yolks you use, the richer your custard will be. If you use skim milk... why even waste your time making this?
You can switch out 1/4 cup of boiling water for the caramel and replace it with a liquor, just wait till the sugar water mixture cools slightly so the alcohol doesn't all evaporate off.