Heat the butter in a large skillet over medium-high heat. Add shrimp in a single layer and cook both sides until opaque in the middle, about 3 minutes. Remove to a cutting board and chop roughly. Set aside.Return the skillet to the stovetop (do not wash it) and add the onion and garlic. Stir and cook for 2 to 3 minutes, or until onion starts to turn translucent. Reduce heat to medium-low. Add dry Arborio rice to the pan and stir it around for a couple of minutes, taking care not to burn it. Pour in wine and stir gently, allowing the rice to absorb the liquid. After the wine is absorbed, begin adding warm broth 1/2 cup to 1 cup at a time, allowing the rice to cook and absorb the liquid each time. Stir occasionally as you go, and add the salt and pepper during one of the broth additions. After 4 cups of broth have been absorbed, taste the rice. It should have a slight bite, but if it seems undercooked, add additional broth and cook it until it absorbs until the risotto is the perfect doneness. Zest and juice the lemon and add both the zest and the juice to the risotto toward the end of cooking. Stir in the heavy cream, the basil, and serve immediately with extra lemon zest and Parmesan cheese on top.