Preheat your oven to 350 degrees F. Prepare a 9x13 inch cake pan with nonstick spray.
In a large bowl or stand mixer, beat together cake mix, 3 eggs, 1/2 cup sour cream, vanilla, and salt. Scrape the bottom and sides well.
Add the mini chocolate chips and the cherry pie filling. You can either fold this in with a spatula if you want your cherries to remain whole, or you can beat it with the mixer. Either way make sure the pie filling is incorporated.
Pour the batter into the prepared pan. Bake the cake at 350 for about 33-35 minutes, or until a toothpick comes out of the center with no batter on it.
Let cool 10-15 minutes, then make the frosting. If you want, use a fork to poke some holes all over the top of your cake. This is so that some of the frosting seeps down, but it's totally optional.
For the frosting:
Melt butter over medium-high heat in a saucepan. Add sugar and milk.
Bring to a boil, stirring very frequently. Once it has reached a rolling boil, remove from heat and let cool 1 minute.
Add the dark chocolate and let sit for another minute.
Stir until smooth.
Immediately pour the frosting over the warm cake.
Serve warm or room temperature. With a tall glass of cold milk please! And don't forget to garnish each slice with some maraschino cherries.
Notes
*6 ounces is 1 cup. Don't stress about this measurement too much. Just dump a little extra on top of your cup.