Soften the butter: Let butter sit at room temperature until it yields to a gentle press but isn’t greasy.
Slightly cool butter whips best.
Beat the butter: In a stand mixer with the paddle (or a hand mixer), beat butter on medium for 2–3 minutes until pale and creamy. Scrape the bowl.
Add sugar gradually: With the mixer on low, add powdered sugar 1 cup at a time. Mix on low until mostly incorporated to avoid a sugar cloud.
Flavor it: Add vanilla and salt.
Mix on low to combine.
Adjust consistency: Add 2 tablespoons cream. Beat on medium-high for 1–2 minutes until fluffy. If it’s too thick, add more cream 1 teaspoon at a time.
If too loose, add a spoonful of sugar.
Whip and smooth: Increase to medium-high and whip for 30–60 seconds for extra lightness. Don’t over-beat or it can trap too much air and create bubbles.
Taste and tweak: Adjust salt or vanilla. For chocolate, beat in 1/3–1/2 cup sifted cocoa powder and add an extra splash of cream.
Use or store: Frost your cooled cake or cupcakes right away, or cover and store as noted below.