Chop hearts of palm; mix them together, in a medium bowl, with the dulse flakes, Old Bay seasoning and lemon juice; coarsely mash with a fork; set aside.
Pre-heat the oven to 400°F.
Cook egg noodles according to package directions; when cooked, drain and add 1 tbsp. butter to noodles to keep them from sticking; set aside.
In a large skillet, over medium heat, add olive oil and butter.
Once melted, add onion, celery and garlic; sauté for 7 to 8 minutes; season well with salt and pepper.
Stir in flour; continue to cook for 1 minute.
In a small saucepan, over medium heat, add broth and milk; remove from heat just before mixture begins to boil.
To the skillet you are already using, slowly wisk in heated broth and milk; continue to cook, stirring continuously, for 3 to 4 minutes or until sauce thickens.
Stir in nutritional yeast; continue to stir until dissolved.
Add mushrooms and frozen peas; continue to cook until heated through; approximately 2 minutes; remove from heat.
Stir in noodles, hearts of palm mixture and 1/2 cup cheese; transfer to a greased 2-quart baking dish; top with remaining cheese and sprinkle crushed chips/crackers crumbs over casserole.
Place in the pre-heated oven and bake, uncovered, for 20 minutes.
Remove from the oven and allow to stand 5 minutes before serving.