In a medium saucepan, bring the water (or milk) and salt to a boil. Slowly whisk in the polenta. Turn the heat to low and simmer gently for about 10-15 minutes, stirring frequently. The polenta should be smooth and creamy and the grains softened. Stir in the grated cheese, if using.

Line a 11 x 8–inch baking dish with parchment paper (or a 13 x 9-inch for thinner squares.) Pour the polenta into the prepared pan and smooth the top. Cool, cover with parchment paper or plastic wrap and then refrigerate until firm, a few hours or up to overnight.

Preheat the oven to 425 degrees. Line a baking sheet with parchment paper and lightly brush with olive oil. Invert the polenta onto a cutting board and cut into 24 equal squares. Brush the tops of the polenta with olive oil and transfer to the prepared baking sheet. Bake 10-15 minutes or until golden. I also like to broil them for an additional couple of minutes. Watch them carefully if you do broil them!

Heat 2 Tablespoons olive oil in a large sauté pan until warm. Add the garlic and sauté until lightly browned. Remove garlic and discard. Add spinach with a sprinkle of salt and toss until wilted. Top the polenta squares with a little spinach and a few capers and serve.