In a medium-sized pan, dry roast the pistachios on medium heat for about 3-4 minutes. Once you can smell the aroma, take it off the heat. Blend the pistachios in a mini food processor until finely chopped, but do not blend it too much else you'll end up with nut butter.

Follow the instructions for your vanilla cake mix, preferably one that uses butter instead of oil. In a large mixing bowl, add the melted butter, milk, eggs, and cardamom powder. Mix well. Then add all the dry ingredients from the boxed cake. Mix until well incorporated but do not over-mix. Add green food color and ½ cup of blended pistachios. Fold into the batter. Butter a 9x13" baking dish and dust some flour to prevent sticking. Pour the batter and bake for 30 minutes or follow your cake mix instructions. Let it cool for about 30 minutes.

Add 1 ¼ cups whole milk, sweetened condensed milk, and evaporated milk in a large mixing bowl. Add cardamom powder, ½ cup of blended pistachios, and green food color. Whisk to mix well. Reserve 1 cup of milk mixture for later. Once the cake cools, poke holes all over the cake about 1-inch apart and pour the remaining milk mixture over the cake. Cover with plastic wrap and refrigerate for at least 6 hours or overnight.

In a large bowl, add heavy whipping cream and vanilla extract. Use an electric mixer to blend for a couple of minutes at medium speed. Then add powdered sugar and beat until stiff peaks form. Do not over-mix.

Remove the plastic wrap. Add large dollops of whipped cream on top of the cake and spread evenly. Top with remaining blended pistachios and a few edible rose petals. Enjoy cold.