Look what I found while visiting BABBLE. They used Nutella, but I hate that stuff, so I substituted peanut butter. YUM! YUM!
1 box chocolate cake mix, prepared according to package directions
1 teaspoon red food coloring
1/2 cup of peanut butter
1 jar cream cheese frosting
3 pint-sized canning jars
Thoroughly wash and dry the inside of each canning jar. Spray the inside of each jar thoroughly with nonstick cooking spray. Set aside.
Stir the red food coloring into the prepared cake batter. Spoon about 1 cup of cake batter into each jar. Cook one jar at a time in the microwave for 1-2 minutes, or until the cake is cooked through. Allow jars to cool slightly, then scoop the top half of cake from the jar. Spoon a tablespoon or so of peanut butter into the center of the jar, top with a dollop of cream cheese frosting and squirt on a little chocolate syrup, then replace the top half of the cake back in the jar, add another layer of peanut butter, a little more chocolate syrup, then enough frosting to fill the rest of the jar. Finally add a few sprinkles.
Serve immediately or cover with a lid and store in the fridge or pop into the mail and surprise someone you love! Cakes should stay fresh in the fridge for up to 5 days, and can be mailed so long as they are topped with a canning jar lid and arrive at their final destination within 3 days.