Pat the shrimp dry. Use paper towels to remove excess moisture so they sear instead of steam.
Season with salt, pepper, paprika, and onion powder. Set aside.
Prep the zucchini. Slice into half-moons about 1/4-inch thick. This helps them cook quickly while staying slightly firm.
Heat the pan. Place a large skillet over medium-high heat.
Add 1 tablespoon butter and the olive oil.
Sear the shrimp. Arrange shrimp in a single layer and cook 1–2 minutes per side, until pink and opaque. Transfer to a plate. Do not overcook.
Sauté the zucchini. In the same pan, add 1 tablespoon butter.
Add zucchini and a pinch of salt. Cook 3–4 minutes, stirring occasionally, until crisp-tender and golden in spots.
Add garlic and heat. Push zucchini to the edges. Add the remaining 1 tablespoon butter to the center.
Stir in minced garlic and red pepper flakes. Cook 30 seconds, just until fragrant.
Bring it together. Return shrimp to the skillet. Add lemon juice and toss everything to coat.
Taste and adjust salt and pepper.
Finish and serve. Turn off heat. Sprinkle with parsley (and Parmesan or lemon zest if using). Serve immediately with extra lemon wedges.