Add the garlic powder, Italian seasoning, cocoa powder, salt, and black pepper to a small bowl and stir to combine. Rub this mixture all over the surface of the chuck roast, pressing firmly to make sure it adheres. Set aside.
Heat two tablespoons of olive oil in a large Dutch oven over medium heat. Once hot, add the seasoned chuck roast and brown on all sides, approximately 3-4 minutes per side.
Once browned, remove the roast from the Dutch oven and transfer to a plate. Add the remaining tablespoon of oil and Portobello mushrooms to the pot and sauté, stirring occasionally, until the mushrooms develop some color and start to release their liquid, approximately 4-5 minutes.
Deglaze the pot by adding the beef broth and scraping up any browned bits on the bottom to incorporate them into the liquid. Stir in the tomato paste and add bay leaves. Return the chuck roast to the Dutch oven and cover.
Reduce heat to low and simmer for 3 to 3½ hours, or until the meat is fall apart tender. Remove from heat and discard bay leaves. Transfer the roast and mushrooms to a serving platter and cover to keep warm. Set aside.
Bring the liquid in the pot to a boil over medium-high heat, then reduce the temperature down to medium for several minutes or until the sauce thickens a bit.
To serve, spoon some of the pan sauce over the beef, along with some of the mushrooms. Garnish with fresh parsley, if desired, and pair with creamy mashed cauliflower, roasted radishes, or your choice of sides. Enjoy!
Macros - per serving*
Net Carbs: 3.59g