First start by preheating the oven to 350F. Then butter an 8 inch circle cake pan and flour it to keep the cake from sticking. Set aside.
Now add the butter and the granulated sugar to a stand mixer bowl. On medium high, cream the butter and sugar for 5-10 minutes or until it is fluffy and light in color. Add in the eggs, one at a time then the vanilla, making sure to mix well between each addition to get them fully incorporated.
Add in the flour, baking powder, salt, and the raspberry powder and mix on low just until the flour has disappeared. Pour the cake batter onto the prepared cake pan and bake in the preheated oven for 30 minutes or until a wooden skewer inserted in the center comes out clean. Let the cake cool down completely before running a sharp knife around the edges and flipping it on a plate.
Making the pink raspberry frosting
In a stand mixer bowl add in the butter and cream using a whisk attachement. You will know the butter is ready when it turns light in color and becomes super fluffy. Add in the cold sweetened condensed milk and the raspberry powder and whip the mixture again for one-two more minutes. Use the frosting right away. If you can't use it right away, rewhip it for 1 minute before using it to get it glossy and shiny.
Frosting the cake
Top the cake with about 1/3 cup of the pink raspberry frosting and spread it over the top. Place the rest of the pink frosting in a piping bag with a 1M wilton tip and pipe little rosettes on top of the cake. Cover the whole cake with rosettes and serve.
If you are not serving the cake right away, you can store it in the fridge just make sure to pull it out an hour or two before serving it to allow the buttercream to soften a little again.