Preheat the oven to 180°C (350°F). Line a large baking sheet with parchment paper and set aside.
In a microwave-safe bowl combine 8 ounces cream cheese, 2 cups shredded mozzarella, and 1/2 cup Parmesan. Microwave in 30-second intervals, stirring as needed, until mostly melted and smooth.
Whisk the 3 large eggs into the melted cheese mixture until smooth to form the lasagna 'noodle' batter. Spread the batter evenly onto the prepared baking sheet.
Bake the cheese batter for 15 minutes, until edges are set and the sheet is firm. Remove and let cool, then slice into 6 even pieces for lasagna sheets.
Heat a non-stick skillet over medium with a little oil. Sauté the chopped large onion and minced garlic for about 5 minutes until softened.
Add 1 pound ground beef to the skillet and cook about 3 minutes, breaking up the meat, then stir in 3/4 cup marinara sauce. Simmer for about 5 more minutes, then remove from heat.
Line an 8 x 8-inch pan with foil. Place two lasagna-sheet pieces on the bottom, spread 1/2 cup ricotta, top with one-third of the meat sauce, and sprinkle 1/2 cup shredded mozzarella. Repeat layers until assembled.
Bake the assembled lasagna at 180°C (350°F) for 30–35 minutes, until the top is golden and the sauce is bubbling. Remove and allow to cool 5 minutes before serving.