Heat a large skillet over medium-high heat. Melt the butter and add in the garlic and fry until fragrant (about one minute). Add in the shrimp and fry two minutes on each side, until just cooked through and pink. Transfer to a bowl; set aside.

Fry the onion in the butter remaining in the skillet. Pour in the white wine (if using), and allow to reduce to half, while scraping any bits off of the bottom of the pan. Add the sun dried tomatoes and fry for 1-2 minutes to release their flavours.

Reduce heat to low-medium heat, add the half and half and bring to a gentle simmer, while stirring occasionally. Season with salt and pepper to your taste.

Add in the spinach leaves and allow to wilt in the sauce, and add in the parmesan cheese. Allow sauce to simmer for a further minute until cheese melts through the sauce. (For a thicker sauce, add the milk/cornstarch mixture to the centre of the pan, and continue to simmer while quickly stirring the mixture through until the sauce thickens.)