Heat the oven to 375°F, then boil the lasagna noodles in salted water until al dente according to the package directions. Drain them and place them in cold water right away so they stop cooking and stay separate instead of sticking together.

Cook the ground beef in a deep pan or Dutch oven over medium-high heat for 2 min, breaking it up as it browns. When the pink is gone, stir in the onion and cook 3 minutes until soft and translucent.

Add the garlic, 1 tsp sea salt, 1/2 tsp black pepper, and 1/2 tsp dried oregano, then cook 1 minute more. The pan should smell savory and fragrant, with the garlic softened but not browned.

Pour in the marinara sauce, bring it to a simmer, then turn off the heat. The sauce should look slightly thick and evenly combined, not watery or greasy.

Spread 1/2 cup meat sauce over the bottom of a casserole dish. This thin layer keeps the noodles from sticking and gives the roll ups moisture from the start.

In a large bowl, mix together the ricotta cheese, 1 large egg, 1/4 cup parmesan cheese, 1 1/2 cups mozzarella cheese, and 1/4 cup parsley. The filling should look creamy and thick enough to hold its shape on a spoon.

Lay the cooked noodles in a single layer on a large baking sheet and blot off excess water if needed. Working flat makes filling and rolling much less messy.

Spread 1/4 cup of cheese mixture over each noodle, then add a heaping Tbsp of meat sauce in a strip down the center. Keep the layer even so the noodles roll neatly without squeezing out too much filling.

Roll each noodle up and place it seam-side down in the prepared casserole dish. A snug roll holds together better during baking than a loose one.

Spoon the remaining meat sauce over the roll ups and top with the remaining 1 1/2 cups mozzarella cheese. Cover with foil, keeping it from touching the cheese so the top stays intact.

Bake covered at 375°F for 40 minutes, then remove the foil and broil for 2 to 3 minutes. The dish is ready when the sauce is bubbling and the cheese is melted with light golden spots.

Finish with more parsley before serving. Let the pan settle briefly so the roll ups lift out cleanly.