3 tablespoons olive oil
1 pound (about 3 to 4) fresh poblano chiles, seeded, ribs removed coarsely chopped
6 garlic cloves, finely minced
1 pound tomatillos, husked, rinsed and quartered
1 1/2 teaspoons salt, plus extra for the shrimp
3 tablespoons unsalted butter
2 pounds large shrimp, peeled and deveined
Freshly ground pepper
4 cups fresh cilantro leaves
Heat the olive oil in a large skillet over medium-high heat for 1 minute. Add the chopped chiles and 1/2 of the garlic and cook until the chiles start to soften, about 5 minutes. Add the tomatillos and salt, reduce the heat to medium-low and cook, stirring occasionally until the tomatillos begin to break down and release some liquid, about 10 minutes.
Transfer the tomatillo sauce to your blender, purée, and set aside.
Melt the butter in a large skillet over medium-high heat. Add the shrimp, season them with some salt and pepper and toss in the remaining chopped garlic. Cook, stirring often, until the garlic becomes fragrant, 1 to 2 minutes. Add the tomatillo sauce and simmer until the shrimp are curled and opaque, 1 to 2 minutes. Serve sprinkled with the cilantro.