Heat your oven to 400°F. While it warms, brush any dirt off mushrooms with a paper towel and trim stems, then tear into 1-inch pieces. Toss them with olive oil, salt, and pepper, spread in one layer on a parchment-lined sheet, and roast for 20–25 minutes, tossing once halfway. You’ll see the edges turn golden and smell a deep, woodsy aroma when they’re done.
As soon as mushrooms come out, transfer them to a bowl and stir in chopped garlic, 1 tablespoon butter, lemon zest and juice, capers, thyme, parsley, and 4 tablespoons breadcrumbs. Give everything a gentle toss and taste, adding more salt and pepper if you think it needs a little boost.
Bring a large pot of salted water to a boil, then add 10 ounces pasta and cook according to package directions until al dente. Before draining, scoop out ½ cup of the hot pasta water, then drain the pasta.
Return the drained pasta to the pot or a large bowl. Add the mushroom mixture, 2 remaining tablespoons butter, and plenty of grated cheese. Gently stir so every noodle gets coated and you see flecks of herbs and breadcrumbs throughout.
Pour in a few tablespoons of the reserved pasta water to loosen things up, stirring until you get a light, creamy coating on the pasta. Give it a final taste, then season with extra salt and cracked pepper to suit your preference.
Place a large nonstick skillet over medium heat with 2 tablespoons olive oil and 1 tablespoon butter. Add the torn bread pieces and sauté for 3–5 minutes, stirring often, until they turn golden brown. Keep an eye on them—they can go from toasty to burnt in seconds.
Add the chopped garlic and ½ teaspoon salt to the skillet and cook for about 30 seconds until you smell the garlic releasing its aroma. Remove the skillet from heat and transfer the breadcrumbs to a paper-towel-lined plate to drain any extra oil. Use these on top of your pasta for a satisfying crunch.