Bring a large pot of salted water to a rolling boil, then add the spaghetti and cook until just al dente, about 8 minutes. Drain, reserving ½ cup of pasta water, and set aside.
While the pasta cooks, heat a large skillet over medium-high heat and add the olive oil. Once shimmering, add the shrimp in a single layer and sear for 2-3 minutes per side until they turn pink and develop crispy edges. Remove the shrimp from the skillet and set aside.
Reduce the heat to medium. Add the sliced garlic to the skillet and sauté for about 30 seconds until fragrant and golden, stirring constantly to prevent burning.
Stir in the smoked paprika and cook for 15 seconds until the smoky aroma becomes fragrant, then immediately add the drained pasta to the skillet. Toss well to coat the noodles in the garlic and paprika oil.
Pour in a splash of the reserved pasta water and toss again to create a silky sauce that coats the pasta evenly. Add the cooked shrimp back to the skillet along with the fresh spinach.
Cook for about 1 minute, stirring gently, until the spinach wilts and everything is heated through. Squeeze fresh lemon juice over the top, then season with salt and pepper to taste.
Transfer the pasta to serving plates, garnishing with additional lemon wedges or herbs if desired. Serve immediately while the shrimp are tender and the pasta is glossy and flavorful.
