Preheat the oven to 350 degrees Fahrenheit.
Melt 2 tablespoons of butter in a large, deep skillet or saucier over medium heat. Add the mushrooms and shallots, sprinkle with a pinch of salt, and saute them for 4-5 minutes, until the shallots turn translucent. Remove them, along with any juices, to a small bowl.
Put the pan back on low heat. Add the heavy cream and cubed cream cheese and whisk until the cream cheese melts. Add one cup of the cheddar cheese in 4 batches, making sure that each previous batch melts before adding more. Finally, add the parmesan cheese and whisk until it melts.
Add the reserved mushroom-shallot mixture and its juices, peas and carrots, tuna, and hearts of palm noodles. Turn the heat back up to medium and bring to a simmer for five minutes.
Pour the contents into a 9x13-inch baking dish and sprinkle the top with the remaining 1/2 cup of shredded cheddar. Bake at 350 for 25 minutes. Let stand for 10 minutes before serving.
Macros per serving: 439 calories, 6 grams net carbs, 20 grams protein, 38 grams fat.
