You can make polenta from scratch for this recipe, but it’s easiest to use leftover. Stir ½ cup of grated cheddar (if using) into leftover polenta and pour into a small casserole dish, about ½-inch thick. You can also simply top polenta cakes with cheese after grilling. If you are starting from scratch, cook ½ cup of polenta according to the instructions on the reverse. When finished, stir in the cheese, pour into a small casserole dish and let cool, uncovered, while you have a glass of wine.
Once cool, cut polenta into four small squares or circles and set on a paper towel to dry. If you’re using leftover, cut polenta into small slices, no bigger than 3-inches square. Heat a pan over medium-high heat. Add two tablespoons of olive oil and sear cakes on both sides, until golden brown. Remove and let rest on a plate. Wipe out the pan with a paper towel. Bring to medium-high heat and add fresh olive oil. Sauté mushrooms with olive oil, a pinch of salt and a sprig of rosemary for two to three minutes until soft. Remove to a paper towel-lined plate. Return the skillet to medium-high heat and add spinach. Season lightly with a pinch of salt. Sauté until tender and wilted. Place two polenta cakes on each plate. Top with spinach, mushrooms and an additional grating of cheddar, if desired.