Prepare the cake mix per the package instructions using the amounts of water, oil and eggs called for. Add 1 Tbsp fresh lemon zest. Bake in a 9 x 13-inch cake until a toothpick inserted into the center comes back clean.
Remove from the oven and immediately poke holes using the back of a wooden spoon or similar over the cake. Be generous.
In a medium size mixing bowl whip the pudding mix and milk until thickened but, still pourable.
Spread over the cake gently pushing into the holes. Cool completely.
To make the frosting, in a medium size mixing bowl using an electric mixer cream together the cream cheese, powdered sugar, lemon juice and lemon extract.
Add the cream continuing to beat until fluffy and fully combined. Mix in 2 Tbsp lemon zest by hand.
Frost the top of the cake and garnish with the remaining lemon zest and grated white chocolate.
May use additional whipped cream and lemon slices to garnish as pictured, if desired.