Adapted from a Simply Colorado recipe, serves about 6. It's very cheap, easy, and healthy, using mostly dry or canned ingredients you already have on hand.
1 1/2 cup - lentils
4 cups - water (or less, it all depends on the size of your pot)
1 cup - beer
qty 2 - bay leaves
3 Tbsp - dry chopped onions, divided
1 tsp - dry ground sage
1 can - diced tomatoes (with seasonings or not, it's your call)
3 oz (1/2 can, typically) - tomato paste
1 1/2 cup - shredded white cheese, divided (just blend together whatever you've got)
1 Tbsp - grated parmesan cheese
1 Tbsp - flour
qty 3 - eggs
2 tsp - basil
1 tsp - oregano
1 Tbsp - bread crumbs (again, seasoned or not, your call)
Preheat oven. Combine lentils, water, beer, bay leaves, 1 Tbsp onions and sage. Bring to a boil, then simmer with lid ajar for 20 minutes or so. I used a nice, neutral Kolsch, but any kinda beer will do.
Meanwhile in a large bowl, combine all remaining ingredients except 1/2 cup cheese and bread crumbs. When lentils are done (if you've never cooked them before, the baggie always has basic instructions), stir them into the big bowl while still hot in order to melt everything together in a nice casserole consistency. Once thickened, pour it all into an oiled baking dish. Sprinkle remaining cheese and bread crumbs on top, hit it with a little cooking spray if you've got it, then bake at 350 F for 45-60 minutes, or until nice and golden brown.
Since you've already got a hot oven going, and some time to kill, let's make a nice side dish too:
Caramelized Baked Carrots
qty 6 or so - carrots
1 Tbsp - brown sugar (same stuff you use in Ditch Stout will suffice)
1 Tbsp - cooking oil
1 Tbsp - freshly grated orange zest (afterwards you might even finish peeling the orange segments to have with dinner too)
Peel carrots and slice diagonally in order to make the pieces as wide as possible. Scatter in oiled casserole dish and microwave awhile to soften. Meanwhile, using a cheese grater or zesting tool, scrape-off the outer skin of an orange. A lemon, clementine, grapefruit, etc, would work fine too. Stir the brown sugar and zest into carrot slices, adding a little more oil to coat if necessary. Cover and bake with your lentil casserole for the same amount of time. It's not an exact science, this'll be delicious at any stage.

Making sure I've got everything before I go too far

Simmering lentils

Stirring-up the carrots

Come and get it!