Place bread on a baking sheet; bake until toasted, 20–25 minutes.
Transfer bread to a cutting board; rub with whole garlic cloves, drizzle with 1⁄4 cup oil, and sprinkle with 1⁄3 cup Parmesan, salt, and pepper. Mince 1 piece of bruschetta; transfer with crumbs to a bowl. Set aside
Heat 1⁄4 cup oil, the sliced garlic, and chile flakes in a 12" skillet over medium heat; cook until garlic is soft, 2–3 minutes.
Add anchovies and their oil; cook, stirring and mashing them up until they melt, 3–4 minutes. Add capers; cook until golden, 3–4 minutes.
Add tomatoes; simmer until sauce is slightly thickened, 4–5 minutes.
Meanwhile, bring a large pot of salted water to a boil. Cook pasta until al dente, about 10 minutes. Drain, reserving 1 cup pasta water and add to skillet with 1⁄4 cup Parmesan, the parsley, and zest; toss.
Garnish with minced bruschetta, remaining oil, and Parmesan; serve with bruschetta.