Preheat oven to 350° F.
Add the lentils to a small pot with enough water to cover them. Bring to a boil, then reduce the heat to a simmer and cook for 15-20 minutes, until tender. Drain and set aside.
Heat olive oil in a medium pan and sauté the onions for 3-4 minutes.
Add the garlic and cook for another 2-3 minutes.
Stir in the celery and carrots and cook for 4-5 minutes, until softened.
In a large bowl, add the chickpeas and cooked lentils. Mash with a fork or potato masher until mostly broken down.
Add the sautéed vegetables to the bowl and mix to combine. Then stir in the oats, nutritional yeast, and seasonings.
Transfer the mixture to a lined loaf pan and press it in firmly.
In a separate bowl, whisk together all the glaze ingredients.
Spread the glaze evenly over the top of the loaf.
Bake for 45 minutes, then let it cool slightly before slicing.