Cube the bread and peel the garlic, add both to a food processor or mini food chopper. Pulse and process until garlic and bread form a uniform medium crumb.
In a large saute pan heat oil and add crumb, shaking constantly until oil is absorbed and breadcrumbs are a deep golden brown.
Remove from heat. add the finely grated lemon zest and mix well to incorporate. Set aside.
For the Linguine and Clam Sauce.
In a large pasta pot, bring salted water to a boil
While water is heating up, add oil to a large high-sided skillet over medium-low heat add garlic and saute until garlic starts to show color (2 minutes). Add the anchovy paste and red peppers. continue to saute until garlic is golden brown and anchovy paste has dissolved. (3 minutes) Add the clam, reserved clam juice, and wine. Stir reduce heat to low and allow sauce to slightly reduce. (approx. 5 minutes.)
Add linguine to the boiling water, cook until slightly under-cooked (about 7 minutes). Drain linguine, reserving 1 cup of the pasta cooking liquid. Add the linguine to the saute pan with the sauce add the butter and and toss until pasta is al dente and most of the sauce is asbsoed. If pasta is too dry add a bit of the reserved pasta water.
Transfer to individual bowls and top with parsley and breadcrumb topping. Serve while hot.