Place the evaporated milk and the condensed milk in your heaviest pot.

Add the cinnamon sticks, baking soda and a pinch of salt.

Stir steadily with a wooden spoon or heat-proof spatula so that the mixture does not stick to the bottom of the pan and burn.

Adjust the temperature so that the mixture stays just barely at a simmer.

Continue to stir until the mixture is making large bubbles, is very thick, and is a golden caramel color. It's very important to stir constantly at this point to prevent burning.

Lift the spoon out of the pot and drizzle some of the caramel sauce over the surface. If it forms a ribbon that does not disappear after 10 seconds or so, it is ready.

Remove from heat and let cool for 10 minutes.

Remove cinnamon sticks and stir in the vanilla and the corn syrup.

Let cool completely.