You need a large bundt pan for this (the traditional one which is 10" ~ most of the specialty pans are smaller 9" pans)
IRISH CREAM PISTACHIO BROWNIE Surprise BUNDT CAKE
1 package dark chocolate fudge brownie mix (family size for a 9x13" pan) plus all ingredients called for on the package. (NOTE: If your brownie mix has a choice to make them fudgey or cake, choose the cake version so it will be closer in texture to the other cake mix.)
1 package butter or yellow cake mix .......................1 small package INSTANT pistachio pudding mix
all ingredients called for on the package. (I substituted Bailey's Irish Cream liquid coffee creamer for the water that was called for. This is non-alcoholic, but you use real Irish Cream liqueur instead too.)
3-4 drops green food coloring (optional)
either 1/2 EACH dark chocolate and white chocolate chips ~ OR~ about 3 squares EACH chocolate and vanilla melting chips or bark ~ PLUS 2 tsp. vegetable shortening and a little green food coloring ** SPRINKLES are optional
Make the brownies according to the package, but use a 10x15" large rimmed baking sheet inside ~ and make sure to liberally spray it (sides too) with non-stick baking spray (containing flour). Cool completely.
When the brownies are completely cool, cut out your shapes with a cookie cutter (as close together as possible). You can use the scraps to make little rectangles to put between your brownie shapes. I put them in little piles on the counter (upside down, since they'll go upside-down into the bundt pan ~ remember that you turn the bundt pan over after the cake has baked!)
Now, make the butter cake mix, using all ingredients called for ~ plus adding the package of pistachio pudding mix and food coloring. Don't forget to substitute the water called for with either Irish Cream liqueur (alcoholic) or Irish Cream flavored coffee creamer.
Line up all your brownie shapes (UPSIDE DOWN) around the inside of your generously-sprayed bundt pan. (You probably won't have enough to go all the way around it, so I put a small rectangle from the scraps between each shape) Gently pour the pistachio cake batter over the brownie shapes and smooth it evenly. Then, I give the pan a quick bang down on the counter, to break any air bubbles inside and help the batter settle down around the brownie shapes.
Bake for about 35-40 minutes, or until it starts to come away from the sides of the pan and a cake tester comes out clean. Cool completely on a rack (in the pan).
When it's cool, turn it over onto your cake plate. Stick some strips of waxed paper or foil under all the edges of the cake, to catch the drips when you drizzle.
I put 1 chocolate at a time into the microwave (in a pyrex measuring cup) with the vegetable shortening, and microwave on HIGH for 1 minute. Then take it out and stir completely with a spoon, until all the chocolate has melted and it's smooth. (When you do the white/vanilla, add about 2 drops of green food coloring before you stir it up.) Now, just drizzle both chocolates over the cake. If you want sprinkles, add them quickly before the chocolate hardens. ** Slide the waxed paper strips out **