While the shrimp stock simmers, devein and coarsely chop the shrimp. (If you'd like to fancy up the risotto, set aside 2 whole shrimp per person as a garnish.)
Heat 2 tablespoons butter in a wide, heavy-bottomed pot over medium-high heat. When the foaming stops, toss in the shrimp, and whole shrimp if using, and sauté until light pink, 3 to 5 minutes. Scrape the shrimp into a bowl.
Return the pot to medium-high heat. Add another tablespoon butter and the shallot and cook until the shallot is translucent, about 3 minutes. Add the garlic and sauté 1 minute more. Lower the heat to medium if needed.
Dump the rice into the pot and stir until each and every grain is well-coated with the butter. Sauté the rice gently for a few moments more until it starts to turn translucent, then add the wine and stir constantly until it has evaporated.
Add the stock by the ladleful (about 1/2 cup at a time) and stir constantly--yes, constantly--until the liquid is absorbed. Repeat until all the stock is used and the rice is creamy and al dente, 25 to 35 minutes. Make sure as you stir to sweep along the entire bottom and sides of the pot to prevent the rice from sticking or scorching.
Stir in the shrimp chunks and the remaining 2 tablespoons butter and allow the shrimp to heat through. Season the risotto with salt and pepper, if you so desire, and spritz it with a little parsley. If you're the fancy schmancy sort, festoon the top of each mound of risotto with the reserved whole shrimp, placing them at a jaunty angle. Serve immediately. And accept accolades shortly thereafter.