Line an 8x8-inch pan with parchment paper, leaving some overhang on the sides. Spray the parchment lightly with cooking oil spray and set the pan aside.
Measure 2/3 cup water into a 2-cup glass measuring cup and heat it in the microwave until boiling.
Add the raw cashews to the hot water and let them soak for at least 1 hour.
Place the soaked cashews and their soaking liquid in a blender. Blend until very smooth, about 1 minute.
Transfer the blended cashew cream back to the measuring cup. You should have just under 1 cup. Add cold water as needed to bring it up to exactly 1 cup.
Place the cashew cream, vegan margarine, and salt in a small saucepan over very low heat. Stir occasionally until the margarine is melted.
Keep the cashew cream mixture warm, but do not let it boil or simmer around the edges. This step should be done on the stovetop, not in the microwave.
While the cream mixture warms, place the sugar, light corn syrup, and 1/4 cup water in a large 4-quart heavy-bottomed saucepan.
Stir until the sugar is evenly moistened, then clip a candy thermometer to the side of the pan. Make sure the sensor is immersed in the sugar mixture but not touching the bottom of the pan.
Place the pan over medium heat and let the sugar mixture come to a boil without stirring.
Continue cooking without stirring until the mixture reaches 300°F to 310°F. If needed, carefully tip the pan to fully immerse the thermometer sensor for an accurate reading.
Remove the pan from the heat. Slowly pour in the warm cashew cream mixture while stirring rapidly until fully combined. The mixture may spatter, so work carefully.
Return the pan to medium heat and continue cooking without stirring until the caramel reaches 245°F.
As soon as the caramel reaches 245°F, quickly remove the pan from the heat.
Without scraping the bottom of the pan, stir in the vanilla extract.
Pour the caramel into the prepared pan and let it cool to room temperature.
Refrigerate the caramel for a few hours, until firm enough to cut cleanly.
Cut into small pieces and wrap each caramel individually in wax paper.
Store the wrapped caramels at room temperature for 1 to 2 weeks, or keep them in the refrigerator or freezer for longer storage.