I tweaked this recipe and it turned out to be the best cake I've ever tasted.
I did not put any lemon in the cake. Instead, I added orange pudding mix (vanilla pudding with Tang added in) Orange zest, the juice of two oranges, 1 small Yoplait Orange Creme yogurt, and orange extract. Reduce the amount of oil, eggs and water to compensate for the orange extract and yogurt. I then made a dark chocolate/orange icing by melting down one large dark chocolate bar (1 lb) and blend in 8 oz cream cheese, 4 oz sour cream, 1 half stick salted butter, 1 tbsp orange extract, orange zest to taste.
Grease 2 9 inch round cake pans and lightly flour. Preheat oven to 350 degrees F
In a large bowl, stir together cake mix and pudding mix, and Tang orange drink mix. Make a well in the center and add water, oil, eggs, yogurt, orange zest, juice from 2 oranges, and orange extract. Beat on low speed until blended. Scrape bowl, and beat 4 minutes on medium speed. Pour batter into prepared pans.
Bake in preheated oven for 40 minutes. When cake tops are rounded, place a plate or any oven safe flat object on top of cakes for 5 minutes to flatten out tops. (this makes for much easier layering and icing)Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely.
In a saucepan over medium heat, melt dark chocolate bar. When melted, remove from heat and add butter, sour cream, cream cheese, orange extract, and orange zest and blend thoroughly. Place icing in refrigerator to cool aproximately 10 minutes. Ice first layer of cake and add top layer and ice top layer. Decorate cake with orange wedges arranged artistically if desired.