Sauté the Aromatics: In a large pan, sauté the onions in a drizzle of olive oil over medium heat until translucent. Add the minced garlic and stir for another minute.

Cook the Lentils: Pour in the dry lentils and then deglaze the pan with vegetable stock. Simmer for 10-12 minutes until softened or al dente, stirring occasionally. Option here to add a bay leaf for extra flavor.

Add the Vegetables: Stir in the grated zucchini and chopped mushrooms to the cooked lentils, letting them cook for another 5 minutes until softened. The mixture should be thick but still moist. Option to add a little cheese into the mixture so you get cheese in every bite.

Assemble the Casserole: Preheat the oven to 375°F (190°C). Transfer the lentil mixture into a casserole dish and spread evenly.

Top with Cheddar Cheese: Leave the cheese out at room temperature to it's soft to grate. Then sprinkle the shredded cheddar evenly over the casserole for a rich, cheesy topping.

Bake Until Golden: Bake uncovered for 15-20 minutes or until the cheese melts and is bubbly and golden brown. Let it rest for a few minutes before serving.