Preheat the oven to 450 and put the cast iron in the oven to heat.
Combine all dry ingredients in a bowl. Combine yogurt, cashew milk, and eggs in another bowl.
When oven is preheated, take the cast iron out of the oven and pour 1 tbsp of the melted butter into the pan and swish it around to coat as much as possible. You can eyeball this. Also, make sure you use an oven mitt. Add remaining butter to the wet ingredients.
Pour wet ingredients into dry, and mix together until everything is just barely combined. Try not to over mix. I find this is best done with a rubber spatula.
Pour batter into the cast iron and place back into the oven.
Reduce the heat to 375 and cook for 20-25 minutes. Test the cornbread to see if it is done by using a toothpick or fork. It will come out clean when it is done.
Allow cornbread to cool for a few minutes and then remove the cornbread from the cast iron. Place a plate on the skillet and flip the pan so the cornbread comes out onto the pan. Once again, use an oven mitt.
Allow cornbread to cool for about 5-10 minutes before slicing.