In a bowl or shallow plate, season shrimp with salt and pepper.

Heat a large skillet over medium heat. Melt 2 tablespoons butter and fry half the garlic and the chopped onion for 1 minute until fragrant — be careful not to burn. Add the riced cauliflower to the skillet and stir to mix everything together well and coat in melted butter. Cook, stirring regularly for 1 minute.

Stir in the 2 tablespoons vegetable stock, about half the parsley, and lemon zest (if using). Cook for one minute to reduce juices then add the lemon juice and ⅔ of the parmesan cheese. Cook for another minute until cauliflower rice is crisp-tender. Remove to a shallow plate and set aside.

In the same pan (clean the pan if cauliflower has burnt), melt 2 remaining tablespoons butter and add seasoned shrimp. Cook shrimp for 1-2 minutes on one side.

Add the remaining minced garlic, Italian seasoning, and onion powder to the shrimp. Stir to combine and flip the shrimp to cook on the opposite side. Cook shrimp for 1 minute then add ¼ cup vegetable stock and Sriracha. Sprinkle shrimp with remaining parmesan, and allow the sauce to reduce for 1 minute, making sure not to overcook the shrimp.

Push shrimp to the side and add cauliflower rice back to the pan to reheat quickly. Adjust seasoning as needed with black pepper and red chili pepper flakes. Stir in the remaining parsley, add lemon slices and serve the garlic parmesan shrimp and cauliflower rice immediately.