If I could take only one frosting recipe with me...
enough to fill and frost a 3 layer x 8” cake or 24 cupcakes
226g unsalted butter, room temperature
1/2 tsp salt
1/2 tsp white vinegar
1 tbsp vanilla bean paste
906g/2 lbs powdered sugar, sifted
~120g heavy whipping cream
Combine the butter, salt, vinegar, and vanilla in the bowl of a stand mixer fitted with a paddle attachment. Mix on medium-low until smooth.
Add in about half of the powdered sugar. Mix on low until mostly incorporated. The mixture will be dry. Add in about half of the cream. Mix on low for ~3 minutes. It should look very smooth.
Add in the remaining sugar. Mix on low. Scrape down the bowl as needed. Add in more cream, 1 tablespoon at a time until desired consistency is reached.
Use the frosting immediately or cover tightly and chill for up to two days in the refrigerator. Bring back to room temperature and mix on low for a few minutes before using.