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 between, until mostly melted and smooth.
Add the 3 large eggs to the melted cheeses and whisk until a smooth batter forms.
Spread the cheese batter evenly onto the prepared baking sheet and bake for 15 minutes, or until the edges are set and firm. Remove and let cool.
While the cheese sheet bakes, heat a little oil in a nonstick skillet over medium heat. Sauté the chopped onion and minced garlic for about 5 minutes, until softened.
Add 1 pound ground beef to the skillet and cook, breaking up with a spoon, about 3 minutes. Stir in 3/4 cup marinara sauce and cook another 5 minutes. Remove from heat.
Line an 8 x 8-inch pan with foil. Slice the cooled cheese sheet into 6 even pieces to use as lasagna 'noodles'.
Assemble the lasagna in the pan: place two cheese pieces on the bottom, spread 1/2 cup ricotta over them, add about one third of the meat sauce, and sprinkle 1/2 cup shredded mozzarella. Repeat to build remaining layers.
Cover the assembled lasagna and bake in the preheated oven for 30–35 minutes, until the top is golden and the sauce is bubbling. Remove and let cool 5 minutes before serving.