Cut the kernels from 2 ears of corn, then cut each cob in half and place in a medium pot. Cover with 5 cups water and bring to a gentle boil.
Pat 500g shrimp dry with paper towel and season with 1 tablespoon Old Bay seasoning and ½ teaspoon salt, toss to coat. Heat a medium skillet on medium and add ½ tablespoon neutral oil just before it hits the smoking point. Add shrimp to the hot oil, working in batches as needed, and sear on high until 80% cooked and a crust starts to form on one side, about 3-4 minutes. Flip and finish cooking, about 1 more minute. You'll know the shrimp are done when they turn pink, opaque and start to curl. Remove and set aside.
Back in the pan, add the kernels and season with salt. Cook gently until bright yellow and warm. Set aside until ready to serve.
By now the water should be boiling, turn heat to low and add ¾ cup polenta, whisking constantly as it simmers until thickened and pulling away from the pan, about 5-10 minutes. Add ¼ cup mascarpone, ⅓ cup grated parmesan and lots of cracked black pepper. Continue whisking until full incorporated—you'll know it's ready when it takes on a pale yellow colour and has the consistency of smooth mashed potatoes. Remove from heat and serve immediately with shrimp, corn and fresh basil.
