Cut eggs in half lengthwise. Scoop out yolks. Reserve whites; place yolks in a large bowl and mash with a fork. Add chopped shrimp, mayonnaise, mustard, dill, lemon juice, garlic salt and black pepper. Stir to combine completely.
Fill each egg white with the yolk and shrimp mixture. Cover and refrigerate until ready to serve.
Place spinach in a large bowl and toss with balsamic dressing. Season with salt and pepper. Slice deviled eggs in half lengthwise and scatter over the dressed spinach salad. Garnish salad with additional cooked shrimp, if desired.