Preheat oven to 350 degrees. Line a 12-cup muffin pan with baking cups and/or spray with nonstick spray; set aside.

In a large bowl, combine cake mix, egg substitute, and 1/2 cup water. Whisk thoroughly. Evenly distribute mixture among the cups of the muffin pan.

Bake in the oven until a toothpick inserted into the center of a cupcake comes out clean, 20 - 22 minutes.

Allow cupcakes to completely cool. Meanwhile, in a small bowl, combine chocolate frosting with chocolate syrup and mix well. Cover and refrigerate.

Once cupcakes have cooled, use a knife or narrow spoon handle to create a small centered hole through the top of each cupcake, stopping about midway through the cupcakes. Set aside.

Open pudding cup and stir in vanilla extract and sweetener. Place pudding in one of the bottom corners of a sealable plastic bag. Remove air and seal. Snip off a small part of that corner with scissors.

Gently squeeze the bag and evenly pipe pudding through the hole in the bag's corner and into the holes in the cupcakes.

Evenly spread frosting-syrup mixture over the cupcakes. (Don't worry if some of the pudding filling gets mixed in!)

Serve and enjoy!