Preheat your oven to 375°F (190°C).
Rinse the lentils under cold water and drain.
In a large pot, combine the lentils and vegetable broth. Bring to a boil, then reduce heat and simmer for about 20 minutes, or until the lentils are tender. Drain any excess liquid and set aside.
In a skillet, heat the olive oil over medium heat. Add the diced onion and garlic, and sauté for 3-4 minutes until softened.
Add the diced carrots to the skillet and cook for an additional 5 minutes until slightly tender.
Stir in the cooked lentils, chopped spinach, oregano, thyme, cumin, salt, and black pepper. Mix well until the spinach wilts and everything is combined.
Transfer the lentil mixture to the baking dish, spreading it evenly.
Sprinkle the shredded cheese evenly over the top of the lentil mixture.
Top with breadcrumbs for an added crunch.
Bake in the preheated oven for 20 minutes, or until the cheese is melted and bubbly.