Start by marinating peeled and deveined shrimp in a mixture of olive oil, snipped parsley, chili powder and ground mixed peppercorns. Let marinate in the refrigerator for about 1 hour. Meanwhile, prepare the sauce by heating some olive oil in a skillet. Add 1 minced garlic clove and crushed tomatoes. Let cook on low heat for 5 minutes. Season with salt and pepper to taste. Cook the spaghetti, according to the package directions. While the pasta is boiling, saute the shrimp in their marinade in a skillet on high heat. Once pink and cooked through, add to the tomato mixture. Drain the spaghetti, and add to the other ingredients. Top with a bit of grated Parmesan and a few black olives. Enjoy!