1 can (21-ounce) cherry pie filling 
1 can (16.5-ounce) pitted dark sweet cherries 
1 box (18.5-ounce) chocolate cake mix 
1 cup chopped walnuts 
3/4 cup butter, cut into pieces 

Preheat oven to 375 degrees F.
 

Spray 9x13-inch baking dish with cooking spray.
 

Dump cherry pie filling into dish and spread evenly. Do the same with the pitted cherries, including the juice.
 

Sprinkle cake mix over the top. Do not stir.
 

Sprinkle with chopped nuts.
 

Distribute butter pieces evenly over the top.
 

Bake for 45 minutes. Once it's done baking, allow cake to cool for 5-10 minutes before serving.