Preheat your oven to 500 degrees. Like 2 baking sheets with parchment paper.
Place the chicken in a large bowl. Make a well in the center of the meat & fill with the breadcrumbs. Moisten them with the milk and add the remaining ingredients, except for the olive oil. Form into 8 large but thin patties & place on the baking sheets. Drizzle each patty with a little olive oil.
Place them in the oven & cook for 15 minutes.
Meanwhile, make your sauce... (if making homemade).
Combine the butter & olive oil in a deep skillet or sauce pan. Add the onions & season with salt and pepper. Cook the onions until they are soft and translucent. Add the minced garlic and cook, while stirring, for another minute. Add the tomato paste & chicken broth and bring to a light boil. Add the tomatoes to the sauce and season with red pepper flakes and oregano. Reduce heat and simmer to thicken a bit.