In a saucepan, heat water, butter, and chocolate. Stir on low heat until melted and combined. Pour into large bowl.
Add both types of sugar to the chocolate mixture and combine using an electric mixer until fully incorporated. Add eggs and vanilla and beat on medium speed for approximately 2 minutes.
Add in flour, salt, and cinnamon and mix on low until well combined. Turn off mixer and stir in the bag of York Minis by hand. Mix well.
Pour batter into greased or sprayed 13x9 baking dish. Bake 22-30 minutes, or until fully cooked. (A toothpick inserted into the middle will come out clear when they are done). Take out of oven and let cool at least 10 minutes before cutting.