Preheat oven to 350 degrees F. Position oven rack in lower-third of oven.
Place deep-dish pie plate, ramekins, or custard cups into an ovenproof roasting or baking pan. If cooking custards in a metal pan, cover the bottom of the pan with a layer of newspaper to ensure an even temperature on the bottom.
Spread brown sugar on the bottom of your baking dish/dishes. Pack into a firm, even layer; set aside.
In a microwave-proof bowl, heat soy milk and vanilla extract until hot; set aside.
In the bowl of your electric mixer, beat eggs, sugar, and salt until combined. Gradually add the warm soy milk until well combined. Slowly pour egg mixture in prepared pie plate or ramekins over the brown sugar. NOTE: Some sugar may float up but will settle to bottom as it cooks.
Bring the water for the water bath (see definition below) to a light simmer on top of the stove; carefully pour hot water into the baking pan to come half-way up the sides of the custard cups. NOTE: The most common mistake people make in baking custard is not putting enough water in the hot-water bath.
Definition of Water Bath or Bain-Marie (bahn mah-REE) - A hot water bath or bain-marie are used to cook custards and baked eggs in the oven without curdling or cracking, and also used to hold sauces and to clarify butter. Water baths are most often used for egg-based dishes. The proteins in the eggs are very heat sensitive and only need to be warmed to cook thoroughly. They will start to get firm at only 145 degrees F. Cooking them with a slow, gentle heat keeps the eggs soft and smooth.
Place roasting pan with pie plate or ramekins in the oven.
Bake approximately 35 to 40 minutes for ramekins or 55 to 60 minutes for pie plate or until set around the edges but still loose in the center. NOTE: The cooking time will depend largely on the size of the custard cups you are using, but begin checking at 20 minutes and check back regularly. When the center of custard is just set, it will jiggle a little when shaken, that's when you can remove it from the oven (the flans will continue to set as they cool). Remove from oven and leave in the water bath until cooled. Remove cups from water bath and refrigerate at least 2 hours or overnight.
To unmold and serve, run a thin knife around the edge of the pie plate or each ramekin to loosen it from the inside of the bowl. Wipe the outside of the mold dry, place an individual chilled serving plate (topside down) on top of each flan. Invert the custard onto the plate and carefully lift off the pie plate or ramekin (shake gently to release flan), allowing caramel syrup to run over flan; pour any extra caramel remaining in the mold over the custard.
Makes 6 to 8 servings (depending on size of the custard cups).
Vanilla Soy Flan with Butterscotch Sauce Recipe: https://whatscookingamerica.net/desserts/vanillaflan.htm