Preheat your oven to 350°F (175°C). Arrange the peeled and deveined shrimp evenly in a baking dish.
In a small saucepan over low heat, melt the butter. Add the minced garlic and sauté for about 30 seconds until fragrant. Alternatively, you can melt the butter with garlic in a microwave-safe dish using a microwave.
Stir the fresh lemon juice into the melted butter and garlic mixture.
Pour the butter mixture over the shrimp in the baking dish. Season with salt, pepper, and red pepper flakes if using. Toss the shrimp to coat them evenly, then spread them out in a single layer.
Bake the shrimp in the preheated oven until they are pink and opaque, which should take around 9 to 13 minutes.
Once baked, sprinkle the dish with freshly minced parsley. Serve immediately, spooning the garlic lemon butter sauce over the shrimp.