While the meatballs are roasting, prepare the sauce. Add 1 tablespoon of butter to the same pan that you cooked the mushrooms in (again, don't wash the pan). Heat over medium heat until the butter is melted. Add the shallots and cook for 1 minute, stirring occasionally.
Add the garlic and tomato paste and cook for 1-2 minutes, stirring frequently, until the tomato paste darkens slightly in color.
Add the red wine, increase the heat to high and bring the mixture to a boil. Boil rapidly for 3-5 minutes until the wine is reduced down to almost nothing - it will have a thick, syrupy consistency.
Add 3 cups of the chicken broth (reserve the remaining half cup), the sliced carrots, cooked bacon, pearl onions, bay leaves, soy sauce, 1 teaspoon of chopped rosemary, 1 teaspoon kosher salt and ½ teaspoon black pepper. Bring the mixture to a boil then cover and reduce to a simmer. Cook for 12-15 minutes or until the carrots are tender.
Add the 2 teaspoons cornstarch to the reserved ½ cup of chicken broth. Stir until smooth.
Uncover the pan and stir in the broth/cornstarch mixture until well combined. Allow the sauce to simmer for 2-3 minutes, stirring frequently.
Add the mushrooms, meatballs, peas and remaining teaspoon of chopped rosemary to the sauce and stir gently. Cover and simmer for 2-3 minutes until everything is heated through. Remove the bay leaves, serve and enjoy!