Preheat your oven to 375°F (190°C).
Prepare the Bell Peppers: Wash and dry the bell peppers. Slice each pepper in half lengthwise and remove the seeds and membranes. Arrange the bell pepper halves in a baking dish with raised sides, cut side up.
Sauté the Beef: Heat 1 teaspoon of olive oil in a large skillet over medium heat. Add ¼ teaspoon of toasted fennel seeds and let them sizzle for about 30 seconds until fragrant. Add 1 pound of lean ground beef to the skillet. Cook, breaking up the meat with a spatula, until browned and cooked through, about 5-7 minutes. Stir in the onion powder, garlic powder, crushed chili flakes, and oregano. Cook for another 2 minutes to blend the flavors.
Pour in 1 cup of marinara sauce and let the mixture simmer for about 5 minutes. Season with 1 teaspoon of salt to taste.
Mix the Cheeses: In a medium bowl, combine 1 cup of whole milk ricotta cheese and ¼ cup of Parmesan cheese. Mix until well combined.
Assemble the Lasagna Boats: Spoon a layer of the beef mixture into each bell pepper half. Add a layer of the ricotta mixture on top of the beef. Repeat the layers, alternating beef and ricotta mixtures, to incorporate cheese throughout. Sprinkle 1 cup of shredded mozzarella cheese evenly over the stuffed peppers.
Bake: Cover the baking dish tightly with foil. Place the baking dish with the stuffed bell peppers in the preheated oven. Bake for 20-25 minutes, or until the peppers are tender and the cheese is melted and bubbly.
Remove the foil from the baking dish. Sprinkle the remaining ½ cup of shredded mozzarella cheese over the top. Return to the oven and bake uncovered for an additional 5 minutes, or until the cheese is golden and melted.
Serve: Remove the bell pepper boats from the oven and let them cool for a few minutes. Transfer the lasagna boats to serving plates and enjoy your delicious Beefy Lasagna Boats!