Spaghetti with Clams and Braised Greens

Name: Spaghetti with Clams and Braised Greens
Ingredients: 1/2 cup extra-virgin olive oil; 8 garlic cloves, crushed; 4 dozen littleneck clams; 2 cups dry white wine; 2 jarred roasted red peppers, drained; 1 teaspoon crushed red pepper; 1 pound Swiss chard or collard greens, stemmed and chopped (8 cups); Kosher salt; Pepper; 1/2 pound spaghetti; 2 tablespoons unsalted butter, cubed and chilled; 1 teaspoon grated lemon zest; 1 tablespoon fresh lemon juice; 1/2 cup grated Parmigiano-Reggiano cheese, plus more for garnish