Preheat the oven to 350℉. Spray a 9X9-inch cake pan with baking nonstick spray. Line the bottom with parchment paper and spray again. Set aside.
In a medium bowl, mix the flour, baking powder, baking soda, and salt. Set aside. Chop the andes mints.
2 1/2 cups All-purpose flour, 1 tsp Baking powder, 1/2 tsp Baking soda, 1/2 tsp Salt, 3/4 cup Andes mints
Using a mixer, beat the butter, oil, and sugar on high speed for 2 minutes. Use a rubber spatula to scrape the bowl.
1/2 cup Unsalted butter, 2 TBSP Oil, 1 cup White granulated sugar
Add in the sour cream, vanilla, and green food dye (3 drops), mix until combined. Add in the eggs and mix on medium speed until smooth. Make sure to scrape the bowl.
1/3 cup Sour cream, 1 TBSP Pure vanilla extract, 3 Large eggs, Green food dye
Add 1/3rd of the dry ingredients and half of the buttermilk and mix on low speed. Add another 1/3rd of the dry ingredients and the rest of the buttermilk. Then, finish with the rest of the dry ingredients.
3/4 cup Buttermilk
Take the batter off the mixer, add in the chopped andes mints. Mix until combined. Pour the batter into the pan.
Bake for 33-36 minutes. Bake until a toothpick inserted comes out clean.
Let the cake sit in the hot pan for 10 minutes. Transfer the cake to a cooling rack. Cool completely before decorating.