1 (828 milliliters) can Italian plum tomatoes, preferably San Marzano, crushed by hand
1/4 cup tiny capers in brine, drained
1/4 cup chopped fresh Italian parsley
Bring a large pot of salted water to boil.
In a large skillet over medium-high heat, add 1/4 cup of the olive oil and the garlic. Once garlic begins to sizzle, add half of the shrimp and the thyme sprigs. Season shrimp with 1/2 teaspoon salt and toss just until the shrimp are seared (but not cooked all the way through), just a minute or two. Remove shrimp to a plate with tongs and repeat with remaining shrimp and another 1/2 teaspoon salt.
Once all of the shrimp has been seared and removed, add zucchini to skillet and cook until wilted, about two to three minutes. Add peperoncino, let toast for a minute, then pour in the tomatoes and slosh out the can with one cup hot water. Season with remaining 1/2 teaspoon salt. Bring sauce to a simmer and cook until zucchini are tender and sauce is thickened, about 15 minutes.In the meantime add fettuccine to boiling water.
Stir the capers in the sauce, return to a boil and add shrimp back. Simmer until shrimp are just cooked through, about two to three minutes.
In the meantime drain fettuccine well add to bubbling sauce toss well quickly. Stir in parsley and drizzle with remaining two tablespoons olive oil. Serve immediately.