Prepare the Base: Heat sardine oil and a drizzle of olive oil in a frying pan over medium heat.
Sauté Vegetables: Sauté chopped onion and garlic, season with salt and black pepper.
Add Ingredients: Add butter, capers, tomatoes, and spinach, and let it cook well.
Add Sardines: When almost ready, add pieces of sardines carefully.
Finish with Parsley: Add a lot of parsley and the sauce.
Cook Lasagna Noodles: Cook dry lasagna noodles according to package instructions and set aside.
Assemble the Lasagna: Start with sauce, then layer with cooked lasagna noodles, alternating layers until desired number is reached.
Final Touch: Top with raw spinach and freshly grated Parmesan cheese.