Meatloaf doesn't have to contain meat! Mushrooms can be used as a delicious substitute for ground beef. They have a similar umami flavor and chewy texture. Mushrooms can be caramelized with onions for extra flavor or blended with onions and garlic in a food processor. Other ingredients like ketchup, herbs, and Worcestershire sauce can be added. For added texture and protein, ground "meat" or crushed nuts like walnuts can be included. This meat-free meatloaf is hearty, savory, and nutritious.