Preheat oven to 350 Degrees F. Grease and flour two 9" cake pans (round or heart shaped).
In a large bowl whisk together the sugar, flour, cocoa powder, baking soda, baking powder and salt.
Add in the eggs, milk, oil, and vanilla extract. Mix on medium speed with an electric mixer for 3 minutes, scraping the sides of the bowl.
Stir in the boiling coffee/water by hand. The batter will be quite thin and liquid consistency. Divide the batter among the two pans. Bake for 30-35 min until an inserted toothpick comes out clean with no batter on it.
Allow cakes to cool in pans for at least 10 min before removing them from pans and setting them on a cooling rack. Cool cakes completely before frosting them.
In a large bowl, cream butter with an electric mixer for about 2 minutes, until it turns lighter in color and fluffy.
Scrape the sides of the bowl, then add the remaining ingredients. If the frosting is too thick and not easily spreadable, add a Tbsp more at a time of milk. If it's too thin, add more confectioners sugar. You don't want the batter too thin or the cake will be unstable.
In a medium bowl, cream the butter until light and fluffy with an electric mixer.
Scrape the sides of the bowl. Add in the remaining ingredients and mix on medium-high until until evenly combined and fluffy.
If the frosting is too thick and not easily spreadable, add a Tbsp more at a time of milk. If it's too thin, add more confectioners sugar. You will want this buttercream to be more on the thicker side, because mixing in the food colouring will thin it out.
Divide evenly into 3 small bowls. One bowl gets "Rose Petal Pink", the second gets "Magenta", and the third gets "Red" food coloring. I ended up combining drops in some of the bowls to get different shades. More drops = more intense color.
On a 10" cake board, place a dollop of chocolate frosting in the center. Place one cake layer upside down on it. Pipe or spread an even layer of chocolate frosting on top of the layer and let it overhang on the sides. Be generous!
Flip second layer upside down and place on top. Using a spatula, spread frosting over top and all around the sides of the cake. Use a cake scraper dipped in a bowl of hot water to get the sides straight and smooth. Dip spatula in hot water bowl to get the top smooth as well. Place cake in fridge to chill.
While cake is chilling, fill piping bags with colored buttercream. Begin with piping the large rosettes first, using Wilton tips 1M and/or 2D. Then for the smaller tips, assemble the piping bags with couplers and fill with colored buttercream. Using tips 16, 21, and 30 pipe smaller designs, filling in gaps or imperfections.
Garnish cake with desired Wilton Valentines' Day sprinkles! Slice, serve, and enjoy!