How to Make It
Pulse garlic cloves in a food processor until finely chopped. Add bread and lemon zest, and pulse until coarse crumbs form. Stir in salt and pepper.
Heat oil in a Dutch oven over medium. Add breadcrumb mixture, and cook, stirring often, until golden brown and crisp, about 5 minutes. Using a slotted spoon, transfer breadcrumb mixture to a small bowl.
Cook pasta in salted water according to package directions. Drain, reserving 1 1/2 cups cooking water. Transfer pasta to a large serving bowl; cover to keep warm.
While pasta cooks, process basil, parsley, Parmesan, oil, pecans, lemon juice, garlic, and salt in a food processor until smooth, stopping to scrape down sides as necessary.
Add pesto and butter to hot pasta; toss gently until pasta is coated. Stir in cooking water, 1/4 cup at a time, until sauce reaches desired consistency. Discard any remaining cooking water. Top with Garlicky Breadcrumbs and Parmesan.