1. Prepare 13″ x 9″ pan with cooking spray and line with parchment paper.  Set aside.
2. Prepare 9″ x 5″ loaf pan with cooking spray and line bottom with parchment paper. Set aside.
3. Preheat oven to 350.
4. In large mixing bowl, combine one cake mix with pistachio pudding dry mix, add 4 eggs, 1 cup sour cream, 1/2 cup vegetable oil, 6 drops green food gel and 1/2 teaspoon vanilla or lemon extract.  Beat 2 minutes until smooth. Pour batter into 9″ x 13″ prepared pan.
5. Bake 9″ x 13″ cake at 350 for 25-35 minutes.  Cover with foil during baking to prevent over browning. Bake until center comes out clean. Remove from oven, cool.  Place pan in freezer for 25-30 minutes.
6. Remove frozen cake, cut 24-30 shamrock cake pieces using shamrock cookie cutter.  Stack the shamrocks solidly together, wrap in plastic wrap and freeze to firm.
7. Meanwhile, mix remaining cake mix, eggs, sour cream, oil, and extract.  Whole eggs will make your batter yellow so if you want a white cake, use egg whites only.  There is no pudding mix in this cake batter mixture.
8. Spoon thick batter 1/3 of the mixture in bottom of 9″ x 5″ loaf pan, spread evenly in pan.  Place unwrapped frozen shamrocks pressed together UPSIDE DOWN in center of cake batter in pan. Shamrock Stems would be facing you.  Cover the mini cakes with remaining cake batter to 3/4 full.  If you have leftover cake batter, make cupcakes.
9. Mix sugar, cinnamon and chopped nuts, spoon over the top of cake batter.
10. Bake at 350 for 35-45 minutes or until done.  Cover with foil to protect from burning.
11. Remove from oven and cool completely.  Remove from pan, crunchy sugar nut side will be on platter.
12. Mix confectioner’s sugar, cream, extract for glaze.  Drizzle over cooled cake and sprinkle with shamrock sprinkles. 

To Serve:  Slice into 1/2″ slices to reveal baked in shamrock cake design.