In a medium heavy-bottomed saucepan over medium heat, add the milk, sugar and baking soda and stir until the sugar has dissolved.

Bring the mixture to a simmer, then reduce to low heat and simmer uncovered stirring occasionally.

Continue to simmer for 1 hour and 30 minutes to 1 hour and 45 minutes, stirring more frequently as the mixture thickens and reaches a deep caramel color.

Skim away any foam that forms on the surface during cooking.

Remove from the heat and stir in the vanilla extract.

Transfer to a heat-proof bowl and allow to cool completely. The dulce de leche will thicken further as it cools.

Enjoy over Vanilla Ice Cream or as a filling or topping for your favorite desserts. Store in an airtight container in the fridge for up to 2 weeks.