Combine the shrimp, lemon zest (save the juice for later!), minced garlic, and spices in a small bowl or ziplock bag and mix well. Let marinate for 10 minutes (up to 1 hour).
In a large stovetop skillet, melt the ghee (or butter) over medium high heat. Once it’s foaming, add the shrimp in a single layer and let cook for 1 minute, until opaque. Flip the shrimp and cook another minute on the opposite side, then transfer to a plate with a slotted spoon, leaving as much ghee in the pan as possible. Set the plate aside.
Add the leeks and fennel to the skillet and saute until caramelized, about 5-7 minutes. If using the wine, add it in now to deglaze the pan, stirring and simmering until most of the wine has cooked off. Add the white beans and bone broth and bring the mixture to a boil, then reduce the heat and simmer for 5 minutes. You want the stew to still be brothy.
Return the shrimp to the pan and stir in the baby spinach. Simmer for 1-2 more minutes, until the spinach is wilted and shrimp is warmed through. Stir in the lemon juice and season with sea salt and pepper to taste.
Ladle the shrimp into shallow bowls and serve with either rice or crusty (gf) toasted bread to soak up the sauce. Garnish with fennel fronds and optional parmesan and enjoy immediately.
