In a large bowl, whisk egg yolks, condensed milk, vanilla, and salt until smooth. Set aside.
In a small sauce pot bring evaporated milk to a simmer.
Slowly add in hot evaporated milk into the egg yolks, whisking constantly, to temper egg yolks so they don’t curdle. Once fully incorporated, strain mixture through a fine mesh sieve and set aside.
Add granulated sugar into a stove top safe baking dish that you will be using to bake the flan in.*
Place dish directly on the burner over low heat and melt until golden brown and caramelized. Only tilt the pan to move sugar around, do not mix as sugar will clump up.
Remove pan from the heat once golden. Let sugar cool in the pan for about 5 minutes.
Pour flan mixture into dish over the caramelized sugar. (if using two dishes divide evenly into each pan). Cover pan with foil and place in a large baking dish.
Transfer to the oven and add in hot water to the baking dish to come 1/2 way up the flan pan.
Bake for 40-50 minutes until flan are set.
Refrigerate overnight. Run a sharp knife around the edge of the flan and invert onto a plate.
Notes
*I used two small llanera pans, so I put 3 Tbsp sugar in each. If making one flan just add all the sugar to the one 8x8 pan.