Pour ½ the chocolate cake mix into a bowl. Shred celery, zucchini and apple directly into bowl and stir well to combine.
Add eggs one at a time, mixing well after each addition.
Pour batter into skillet, turn heat to medium, and cover. When Vapo-Valve™ clicks, reduce heat to low and cook for approximately 10 - 15 minutes. Cake is done when a knife inserted in centre comes out clean.
Flip cake onto serving platter and place Hershey's chocolate bar on top of hot cake. Allow chocolate bar to melt, spreading chocolate evenly over cake.
Top with sliced strawberries. Garnish with white chocolate shavings, if desired.