Heat the olive oil in a large skillet over medium-high heat until shimmering. Add the diced onions and cook, stirring occasionally, for 3–4 minutes until softened and translucent. Add the ground beef, breaking it apart with a wooden spoon, and cook for 5–6 minutes until well browned — you should hear a steady sizzle, not steaming. Add the minced garlic and cook for 30 seconds until fragrant. Stir in the salt, oregano, and paprika. Pour in the preserved tomatoes, stir to combine, and simmer for 5 minutes until the sauce has thickened slightly. Remove from heat and set aside.

Mix the cottage cheese, half the Parmesan, the pesto sauce, the sour cream, and the egg yolk.

Cook the lasagna pasta according to package instructions, then let them cool down. Grease them with oil so that they don't stick together.

Preheat the oven to 375°F / 190°C (170°C fan-forced).

Lightly grease a 9x13 inch (23x33cm) baking dish. Spread a thin layer of meat sauce across the bottom. Lay down a single layer of lasagna sheets (trimming to fit if needed). Spread half the remaining meat sauce evenly over the sheets, then top with half the cottage cheese mixture.

Add another layer of lasagna sheets, then the remaining meat sauce, another layer of sheets, and the remaining cottage cheese mixture. Finish with a final layer of lasagna sheets. Spread the shredded mozzarella evenly over the top and sprinkle with the remaining grated Parmesan.

Bake at 375°F / 190°C (170°C fan-forced) for 20–25 minutes until the top is golden brown and the cheese is bubbling. Let it rest for 10 minutes before slicing — this allows the layers to set and makes for much cleaner portions.