Frosting, aka the fluffy, sweet, buttery spread that goes over cakes, cookies, and cupcakes, isn't so hard to make homemade if you set yourself up for success. First, you must have a large bowl and a hand mixer or stand mixer. If you don't own either, a hand mixer is significantly cheaper. If a whisk is what you're working with, consider making whipped cream instead of frosting.
Next, silky smooth frosting requires a little planning. You must put the butter (and cream cheese) out a few hours prior to come to room temperature. Otherwise, if you try to whip them up cold, the frosting may turn out lumpy or dense. Spreadable fluff is what we're after, and that can only be achieved if the fats are whipped at room temperature! Lastly, always sift the powdered sugar (and cacao powder if applicable) before whipping into the frosting. Once again, if you skip this step, your frosting may turn out as lumpy as tapioca pudding and there's no turning back. No, thanks!
Now that you're ready to beat all the ingredients together, here's the basic technique: In a large bowl, whip the softened butter (and sometimes cream cheese) until it becomes light and fluffy. Slowly mix in the sifted powdered sugar a little at a time until a thick paste forms. Next, whip in the vanilla. Lastly, add the milk one tablespoon at a time and beat for another few minutes or so until you reach a fluffy, spreadable consistency. I personally love using heavy whipping cream in place of milk so that the icing becomes voluminous and whips up almost like whipped cream. That's it! Now, you're ready to decorate your dessert.
One thing to note: do not refrigerate buttercream. It should have enough sugar to preserve it at room temperature for a few days. If you refrigerate the buttercream, it will stiffen up like butter and you'll need to let it come to room temperature (and rewhip it a few minutes using the mixer) before attempting to frost your treats.
Now that you're ready, here are a few classic frostings to get you started.
Softened butter + sifted powdered sugar + vanilla + milk (or heavy whipping cream)
Get the recipe: basic buttercream
Softened butter + sifted powdered sugar + sifted cacao powder + vanilla + milk (or heavy whipping cream)
Get the recipe: chocolate buttercream
Cream Cheese Frosting
Softened butter + softened cream cheese + sifted powdered sugar + vanilla + milk (or heavy whipping cream)
Get the recipe: cream cheese frosting
A few of my other favorite additions to frosting are salt and citrus zest. If you love cookies with salt on top or salted caramel, then you'll get a kick out of adding a few teaspoons of salt to buttercream. Another easy way to add flavor is by mixing the zest of lemon into the frosting, although lime, grapefruit, and orange will also work.