In a mixing bowl, combine shrimp, minced garlic, lemon juice, paprika, and half of the cracked black pepper. Toss to coat evenly.
Heat olive oil in a frying pan over medium heat. Once hot, add the shrimp mixture and cook for 3–4 minutes until the shrimp turn pink and opaque. Remove from heat and set aside.
In the same pan, add the chopped kale and spinach. Sauté for 2-3 minutes until wilted, then return the shrimp to the pan, mixing everything gently.
Toast the slices of whole-grain bread until golden brown.
Assemble the sandwiches by layering the shrimp and greens mixture onto two slices of toasted bread. Top with the remaining slices to close the sandwiches.
Cut the sandwiches in half and serve with a simple side salad sprinkled with remaining black pepper.
