In a medium skillet, heat 2 tablespoons oil and the butter over medium heat until butter is foamy. Add breadcrumbs, season with salt and pepper, and cook, stirring, until breadcrumbs are golden brown; set aside.
Bring a large pot of water to a boil, and add salt. Add bucatini, and cook until al dente according to package instructions.
Meanwhile, heat remaining 3 tablespoons oil in a large skillet over medium heat. Add roasted garlic and sliced garlic. Cook, stirring, until garlic infuses oil. Use tongs to transfer pasta directly from the boiling water into the pan with the garlic and oil. Toss to combine.
Transfer to a large platter. Sprinkle with toasted breadcrumbs. Use the large holes of a box grater to shave the bottarga over the pasta. Serve immediately sprinkled with grated cheese and accompanied by herb toasts.