Step 1 In a large, heavy-bottomed pot, heat milk until it just starts to steam. Gradually pour in the polenta, whisking constantly to avoid lumps. Adjust the heat to medium and cook, stirring occasionally, until the polenta begins to bloom and absorb the milk, about 10 minutes.
Step 2 Once the polenta begins to simmer, reduce the heat to low, stirring constantly so it doesn't burn. Continue to cook until the graininess is gone and the polenta is rich and creamy, 20 to 30 minutes more, adding additional milk if needed. The polenta should be the consistency of a soft, creamy pudding and move easily when you shake the pot. Remove from heat and add the mascarpone and Parmigiano-Reggiano, along with the butter and 1 tablespoon salt. Hold in a warm place until ready to serve. (This makes about 6 cups polenta, more than is needed for the remainder of the recipe; the extra polenta can be chilled and reheated before serving, and it will keep up to 2 days.)
Step 3Heat a sauté pan large enough to hold all the cauliflower leaves without crowding, or work in batches. Coat the pan with about 2 tablespoons of olive oil over medium-high heat until just shimmering. Add the cauliflower leaves and sauté quickly until they barely wilt and start to become tender but are still bright and crunchy, 5 to 6 minutes. Season with 1/2 teaspoon salt, or to taste, and freshly cracked black pepper.
Step 4Spoon the warm polenta into individual bowls or a large serving bowl (approximately 1/2 cup polenta for each serving). Spoon the leaves on top of the polenta and sprinkle with a little Parmigiano-Reggiano cheese to garnish, crack some pepper on top and drizzle liberally with extra-virgin olive oil.