Preheat oven to 350 degrees. Saute onion in oil until golden brown over medium heat. Add ground sirloin and cook thoroughly. Season with salt and pepper, add spinach, cook for two minutes, add garlic and flour and cook for 3 minutes. Add half and half and cheese and cook stirring until cheese is melted.
Fill shells with mixture.
Sprinkle with extra cheddar cheese. Bake for 10 minutes. Top with dill pickle. Drizzle with ketchup and mustard.