Combine shrimp with next 6 ingredients and toss to coat shrimp evenly.
Heat a large, nonstick skillet over medium high heat, then add half of the shrimp. Cook shrimp 3 minutes until pink and just firm. Remove shrimp to a warm platter and repeat process with remaining shrimp.
Return pan to heat and reduce heat to medium low. Add 1/4 cup extra-virgin olive oil. Add anchovies, garlic, and pepper flakes to oil. Break up anchovies with a wooden spoon until they melt away into the oil and garlic mixture.
Toss spaghetti in the pan with parsley and the garlic oil, then season with a little coarse salt, to your taste. Top servings of garlic and oil spaghetti with spicy shrimp and serve with Tomato and Onion Salad and Crusty Bread.
Prep your garlic and parsley for aglio olio and set them, as well as drained pasta and remaining ingredients all within arm's reach of your stove top.
The aroma will be intense! Cooked anchovies have a salted-nutty (rather than fishy) taste that compliments the garlic as it sweetens and softens.
Tomato and Onion Salad:
Toss the tomatoes and onions with the chopped parsley, oil, salt, and pepper. Let stand while you prepare dinner, about 20 minutes. Re-toss and serve salad with crusty bread for mopping up juices and oil.