Preheat the oven to 350°F (175°C). While the oven is heating, heat the oil in a large pan over medium heat. Add the diced onion and sauté for about 3 minutes, or until softened. Add the shredded carrots and continue to sauté for another 2 minutes, stirring occasionally.
Step: 2
Add the ground beef to the pan and season with salt, pepper, and garlic powder. Break up the beef with a wooden spoon and cook for about 10 minutes, stirring occasionally, until browned and fully cooked. Make sure to separate the beef as it cooks to ensure even browning.
Step: 3
Add the marinara sauce and mix until fully incorporated with the beef mixture. Sprinkle in the flour and cook for an additional 3 minutes, stirring constantly. This will help absorb any excess liquid and thicken the mixture.