In a large mixing bowl, sift flour, baking powder, baking soda and cocoa. Add salt. In a separate bowl, add oil, buttermilk, sugar, vanilla, food coloring and eggs. Mix well. Begin to add 1/2 cup of flour mixture to the sugar mixture and mix until combined. Keeping adding about a 1/2 cup of flour mixture until well mixed.
If you don't have buttermilk, substitute sour milk: 1 tbsp of lemon juice or white vinegar to a measuring cup and fill the remainder up to 1 cup with whole milk. Let stand 5 min before using.
Pour cake batter into 24 cupcake liners filling no more than 2/3 full. Bake for 15-18 min in 350F or 180C oven. Let cool 30 min before applying icing and decorations.
With an electric mixer, cream 1 1/2 sticks butter in a large mixing bowl.
Slowly beat in the confectioner's sugar until smooth and creamy and sweetened to your liking (about 2 minutes).
Add a tablespoon of milk if icing is too thick to spread on cake.
The prep time includes making the cupcakes from scratch and decorating them.You can cut the pretzels and unwrap the Ferrero Rocher pieces while the cupcakes are baking.Store cupcakes in the refrigerator.