In a large bowl, mix ground chicken, breadcrumbs, egg, milk, chopped onion, garlic, Worcestershire sauce, salt, black pepper, and smoked paprika until well combined
Shape the mixture into 4 oval patties
Heat olive oil in a skillet over medium heat and cook the patties for about 4-5 minutes per side until golden brown, then remove from the skillet
In the same skillet, melt butter and sauté mushrooms until softened
Add broth, Worcestershire sauce, tomato paste, Dijon mustard, salt, and black pepper, stirring to combine
Bring to a simmer, then add the cornstarch mixture to thicken the gravy
Return the patties to the skillet and let them simmer in the gravy for about 5 minutes until fully cooked
Serve hot with mashed potatoes, rice, or vegetables