First toast the cornmeal. To do this, heat a large cast-iron skillet or heavy-bottomed pan over medium heat, then add the cornmeal and toast for around 10 minutes or until it turns a golden brown, stirring frequently to prevent burning and ensure that the cornmeal toasts evenly. The cornmeal will turn from a white color to a light brown. Remove from heat and reserve.

In a large saucepan over medium heat, bring the water, maple syrup, salt, and culinary ash (if using) to a boil. Whisk in the toasted cornmeal, lower the heat to a simmer, and cook for 30 minutes, stirring frequently with a heatproof rubber spatula or whisk to prevent burning.

After 30 minutes, transfer the mixture to a heatproof container or containers so that it comes up the sides approximately 1 inch. Let cool to room temperature before covering and freezing overnight. Place in an oblong, flat, hard plastic container so that it is easy to cut into small squares for serving after it has frozen, and then freeze.

Remove from the freezer and let thaw for approximately 40 minutes before turning it out on a cutting board and slicing into small squares. Serve with a drizzle of additional maple syrup if desired.