Baked Polenta with Vegetables (Mămăliguță cu Legume la Cuptor)

This is serious comfort food.  Every bite is like a piece of heaven. Polenta or cornmeal mush is super popular in Romania, where I grew up.  It actually replaces bread for most of the meals. In this dish, it is the perfect complement to all those delicious veggies.  Top with all with some mozzarella and you get the perfect dish!  Enjoy!
-4 cups water, divided
-3 tsp salt, divided
-1 1/2 yellow cornmeal
-2 Tbs extra virgin olive oil
-1 onion, thinly sliced
-16 oz baby portabella mushrooms, sliced
-1 tsp pepper
-2 (16 oz each) jars roasted red peppers, drained and cut into thin strips
-1 1/4 cups marinara sauce
-1 1/2 cups shredded mozzarella cheese
Start by making the polenta.  Bring 2 1/2 cups of the water combined with 1 tsp of the salt to a boil.
In a medium bowl, combine remaining water with 1 tsp of the salt and the yellow cornmeal.  Pour into boiling water and mix well.  When it starts boiling again, lower the heat and simmer, stirring occasionally, for about 5 minutes.
Pour polenta into engrossed 9x13 baking dish.  Spread evenly and refrigerate for 30 minutes.
While that's cooling, preheat the oven to 350 F.
Heat oil in large skillet.  Add the onion and mushrooms.  Season with remaining salt and pepper.  Cook for about 10 minutes or until vegetables are nice and tender.  Remove from heat and add the pepper strips.  Mix well.
Remove polenta from fridge and top with marinara sauce.  Spread evenly.  Top with veggies and any juices from the pan.  The polenta will soak all that up beautifully.  Top with the cheese.
Cover with foil and bake in preheated oven for 30 minutes.  Remove foil and bake for 15 more minutes.
Remove from oven, slice and enjoy a piece of heaven!