Creamy Corn Miso Pasta

Name: Creamy Corn Miso Pasta
Ingredients: 8 ounces campanelli pasta (about 3 cups); 2 (10-ounce each) ears fresh corn, shucked (1 ½ cups corn kernels); 3 tablespoons unsalted butter; 1 yellow onion, finely chopped (about 1 cup); 3/4 teaspoon grated garlic (from 2 small cloves); 1/2 cup water; 2 tablespoons white miso; 1/2 teaspoon gochugaru flakes (Korean chile flakes); 4 tablespoons chopped fresh chives, divided; 1 ounce Parmigiano-Reggiano cheese, grated (about 1/4 cup), plus more for garnish; 1 tablespoon fresh lemon juice; Kosher salt, to taste