Slow Cooker Buffalo Chicken Pizza Loaf

Spray the inside of a slow cooker with cooking spray. Bring milk to a boil in a small saucepan and remove from heat; let cool until lukewarm, about 10 minutes. Pour milk into a large bowl and stir in honey and yeast. Let the mixture stand until yeast begins to foam, about 5 minutes. Mix flour into milk mixture, 1 cup at a time, until dough is no longer sticky. Knead dough until elastic, about 2 minutes. Combine chicken and onion in a bowl; stir hot sauce into chicken mixture. Roll dough into a 12-inch circle and fit dough circle into slow cooker. Sides of dough circle may collapse. Pour tomato sauce inside dough, lifting dough sides if needed. Fill inside of dough with chicken mixture and top with 3/4 cup mozzarella cheese. Fold sides of dough over filling and sprinkle with remaining 1/4 cup mozzarella cheese. Cook on High until crust is cooked and filling is hot, about 2 1/2 hours. Cool slightly before serving.