Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan. Pour ½ cup of melted unsalted butter evenly into the bottom of the pan, then sprinkle 1 cup of brown sugar over the butter, creating a sweet caramel layer. Spread 1 can of cherry pie filling over the brown sugar, ensuring it's distributed evenly for a luscious topping.

In a large mixing bowl, combine 1 package of chocolate cake mix, 3 large eggs, ½ cup of vegetable oil, 1 cup of water, and 1 teaspoon of vanilla extract. Mix using an electric mixer on medium speed for about 2 minutes, or until the batter is smooth and well blended.

Carefully pour the prepared chocolate cake batter over the cherry layer in the baking pan, making sure to cover it evenly. Use a spatula to gently spread the batter into the corners of the pan.

Place the assembled Chocolate Cherry Upside Down Cake in the preheated oven and bake for 35 to 40 minutes. The cake is done when a toothpick inserted into the center comes out clean or with few crumbs attached.

Once baked, remove the cake from the oven and allow it to cool in the pan for about 10 minutes. After cooling, place a serving platter over the cake, then carefully flip the pan over to release the cake onto the platter, revealing the gorgeous cherry topping.