How to Make It
In a saucepan, bring 6 cups of water to a boil. Slowly drizzle in the polenta, whisking constantly. Bring to a simmer and cook over moderately low heat, stirring, until tender and thickened, 20 minutes. Stir in the butter, 2 tablespoons of oil and the grated cheese; season with salt and pepper.
In a blender, puree the Swiss chard with 1/2 cup of water until smooth. Scrape into a small bowl. Wipe out the blender. Add the beet and 1/2 cup of water and puree until smooth. Scrape into another small bowl.
Pour half of the polenta into a bowl. Add the chard puree to the remaining polenta in the saucepan and cook over low heat, stirring, until well blended, 2 minutes. Mound the chard polenta on one side of each of 6 shallow bowls. Rinse out the saucepan and add the reserved polenta and beet puree. Cook over low heat, stirring, until blended, 2 minutes. Spoon the beet polenta next to the chard polenta. Top with the ricotta salata, garnish with arugula and drizzle with oil. Season with pepper and serve.