Beat the butter on a medium speed for 30 seconds with a paddle attachment, until smooth.
Slowly add in the powdered sugar, 1 cup at a time. Alternate with small splashes of cream.
Once fully mixed, add in the salt.
Beat on low until the ingredients are fully incorporated, and the desired consistency is reached.
If the frosting is too thick, add an extra Tbsp of heavy cream. If it's too thin, add in another 1/2 cup of powdered sugar.
Stir by hand with a rubber spatula to get the frosting SUPER smooth.
Place 2 cup of vanilla buttercream into a small piping bag, and seal with a rubber band. Cut a small, 1 cm opening at the end and set aside.
Color 1/4 cup of frosting orange with gel food coloring, and a 1/4 cup pink with gel food coloring. Place each color in its own, small piping bag. Snip a small opening that is about 1/3 cm wide.
Add in the sifted cocoa to the remaining buttercream, and mix on low until the cocoa is fully incorporated.
Mix in the cooled, melted chocolate, and a squirt of black gel food coloring. Stir until the frosting is evenly colored.
Place 1/4 cup in a small piping bag fitted with a small round piping tip.
Place the remaining frosting in a large piping bag, and seal the top with a rubber band. Cut the tip of the bag to have a 1.5 cm opening.