- Open vanilla bean and scrape out seeds. Reserve seeds for another use.
- Combine goat's milk, sugar, and vanilla bean pod in a large, heavy-bottomed pot. Warm over medium heat, stirring occasionally with a heat-resistant or wooden spatula, until sugar is completely dissolved. Milk should turn foamy and light in about 15 minutes.
- Dissolve baking soda in a few tablespoons of water and add to pot. This will help keep milk from curdling. Mixture will foam when baking soda is added. Remove from heat briefly and stir until mixture stops foaming, then return to heat.
- Once milk mixture comes to a gentle simmer, reduce heat to low and let it cook, stirring frequently, for about 45 minutes up to 2 hours, or until it's thick and caramel-colored. The exact cooking time will depend on the size of your pot, the heat of your stove, and your desired consistency. A good stopping point is when it becomes the consistency of a thin jam, and it leaves an open trail for at least 1 second when you scrape a spatula across bottom of pot. Stir more frequently as cajeta thickens to prevent scorching. Scrape bottom of pot regularly to prevent milk from sticking and burning.
- Once it has reached your desired consistency, remove vanilla bean and let it cool. Cajeta will thicken more as it cools.
- Pour cajeta into a clean, heat-resistant jar. If total amount is less than 1 cup, thin it with a very small amount of water or goat's milk. This will prevent it from becoming too thick once it cools.
- Store cajeta in a refrigerator. It should keep for up to a month.
NOTE: Making cajeta is not tricky, but it does require patience and frequent stirring, especially as it starts to thicken.