1/2 teaspoon kosher salt, plus more as needed
3/4 pound large shrimp (340g), shelled and deveined, shells reserved
Large pinch baking soda
6 tablespoons extra-virgin olive oil (90ml), divided
4 medium cloves garlic, thinly sliced
1 1/2 teaspoons dried oregano
1 to 2 teaspoons red chili flakes (see note)
2 tablespoons (30ml) brandy (optional)
1 (28-ounce; 795g) can whole peeled tomatoes and their juices, coarsely pureed or crushed by hand
1/2 cup bottled clam juice (120ml)
1 pound spaghetti (450g)
1/4 cup minced flat-leaf parsley leaves and tender stems (from 1 small bunch)
Step 1: Bring a large pot of salted water to a boil. In a medium bowl, toss the shrimp well with the 1/2 teaspoon salt and the baking soda. Set aside.
Step 2: In a large skillet or sauté pan, heat 4 tablespoons olive oil over medium-high heat until shimmering, Add reserved shrimp shells and cook, stirring constantly, until they've all turned a reddish color, about 4 minutes. Off the heat, remove the shells using tongs, a slotted spatula, and/or a slotted spoon, allowing any excess oil to drain back into skillet as you go; discard the shells. You should still have plenty of oil left in the skillet.
Step 3: Return the skillet to medium-high heat, add the shrimp, and cook, stirring and turning occasionally, until shrimp are just starting to brown in spots and are almost fully cooked through, about 3 minutes. Off the heat, transfer shrimp to a plate and set aside.
Step 4: Return the skillet to medium-low heat. Add garlic, oregano, and chili flakes and cook, stirring, until garlic is just beginning to turn golden, about 3 minutes. Add brandy, if using, and cook until almost fully evaporated. Add tomatoes and clam juice and bring to a simmer. Season with salt.
Step 5: Boil the pasta in the pot of salted water until al dente. Drain, reserving about 1 cup of the pasta cooking water, and add pasta to the sauce along with a splash of the pasta cooking water. Add shrimp and cook over medium-high heat, stirring, until the sauce reduces and clings to pasta and the shrimp are fully heated through; add more pasta water as necessary if the sauce becomes too dry. Season with salt, if necessary.
Step 6: Stir in parsley and remaining 2 tablespoons olive oil. Serve right away.
Step 7: Notes: Red chili flakes can vary greatly in their heat intensity, as does personal tolerance for heat. The quantity given here is a rough estimate, but follow your own judgement based on the strength of your chili flakes and the degree of heat you want.