Lightly grease an 8-inch squared baking dish; set aside. Heat a large saucepan over medium heat. Add the olive oil and butter to the pan. Allow them to melt and heat up until the butter has fully melted and starts to bubble. Once the butter is bubbling, add the smashed garlic to the pan. Sauté the garlic in the heated oil and butter mixture for about 4 minutes, stirring constantly. Be careful not to let the garlic burn or turn brown, as it can become bitter. Discard the Garlic.

Add the water, salt, and pepper to the butter mixture. Increase heat to medium-high heat and bring it to a boil. Add the cornmeal in a slow, steady stream, whisking constantly. Reduce heat to medium-low and continue to cook, whisking frequently and scraping the sides and bottom of the pot until the mixture is thick and the cornmeal is tender, about 20 minutes. Off the heat, whisk in the freshly grated Parmesan Cheese and half and half. Transfer to the prepared dish and let cool. Once cooled, cover tightly with plastic wrap and refrigerate until completely chilled, about 3 hours.

Heat the oil and butter in a 14-inch nonstick pan or work over medium heat. When the oil and butter mixture is hot, add the onion and cook, stirring until lightly brown, about 4 minutes. Add the garlic and cook, stirring, until it begins to color about 1 to 2 minutes. Add the crushed tomatoes, rinse the can with 1 cup of water, and add the water to the pan—season with kosher salt, red pepper flakes, and sugar. Bring to a boil, reduce heat to medium-low, and simmer until sauce is slightly thickened and flavorful about 15 to 25 minutes. Taste and adjust the seasoning with more kosher salt and red pepper flakes if needed. Remove from heat; cover and keep warm.

Adjust the oven rack to a middle position and heat the oven to 375 degrees F. Line rimmed baking Sheet with Parchment Paper, then grease parchment. Cut chilled Polenta into 6 equal pieces. Place on prepared baking sheet and bake until heated through and begin to brown on the bottom, about 30 minutes. Serve each portion covered with about ½ cup tomato sauce.