Preheat oven to 375 degrees F (190 degrees C). Grease a 9x5-inch loaf pan.
Heat oil in a large skillet over medium heat. Add onion and garlic and cook until softened, about 5 minutes. Add mushrooms and cook until softened, about 10 minutes. Let cool.
In a large bowl, mix together the cooled mushroom mixture, ground chicken, bread crumbs, eggs, ketchup, Worcestershire sauce, oregano, salt, and pepper. Mix until well combined.
Press the mixture into the prepared loaf pan and spread ketchup over the top. Bake in preheated oven for 40 minutes, or until the internal temperature reaches 165 degrees F (74 degrees C).
Let cool for 10 minutes before slicing and serving.
Interesting Facts
The name meatloaf comes from the 19th century when the dish was a mixture of ground meat, vegetables, and other ingredients, all formed into a loaf shape.
Adding mushrooms to your meatloaf can help to reduce the fat content and add additional flavor.
Meatloaf is a great way to use up leftover vegetables.