Pulse millet in a food processor or blender, roughly 4 to 6 time, until the mixture resembles a course flour/meal.

Heat a medium pot over medium-low heat. Add the millet and toast the cracked grain for a couple minutes, until the millet becomes fragrant.

Add the vegetable broth, water, and salt. Bring to a boil, reduce to the lowest heat, and cook for about 18 to 20 minutes, whisking frequently.

Polenta should be thickened and any pieces of millet should have softened. If needed, add a splash more water to thin the polenta and cook for longer. Remove from heat and stir in the butter/cheese if using, whisking until smooth.