Preheat oven to 350 and line a 10x15x1 baking sheet with parchment paper. Spray the parchment paper with nonstick cooking spray. Set aside.

Line 1 muffin tin with 5 paper liners and set aside.

Add eggs to a mixer and beat on high for 5-6 minutes until bubbly and frothy. Add cake, water and oil. Beat for 30 seconds on low and scrape down the sides of the bowl. Beat on medium for 1 minute until combined well.

Pour 3-½ cups of batter into prepared baking sheet. Spread batter evenly. Use a 3 tablespoon portion scoop to scoop remaining batter into 5 cupcake liners.

Bake for 14-16 minutes or until cake is done in the center when a toothpick is inserted in it. Remove from oven. Cool cupcakes completely before frosting and enjoying.

For the cake roll, generously sprinkle powdered sugar onto a thin, clean towel. Let the cake cool for 10 minutes before removing it from the pan and placing it onto the powder sugar covered towel. Discard the parchment paper. Starting on a short end, roll the towel and cake into log shape. Set aside to cool completely.

To make the buttercream frosting, beat butter for 2 minutes. Add powdered sugar and vanilla and beat slowly and then on high for 2 minutes. Add cream until you have the right spreadable consistency. Fold in sprinkles.

Carefully unroll cooled cake roll and spread icing on the top. Roll back up and wrap with plastic wrap. Refrigerate for 2 hours or until ready to serve. When ready to serve, unwrap and melt chocolate according to package directions. Drizzle on top of cake roll and sprinkle with Valentine sprinkles. Let stand for 10 minutes to harden.

To serve, slice into 12 slices, about 1" wide.

Store any leftover cake roll covered and in the refrigerator.