Brown the Butter: Add the butter into a large frying pan and cook over medium heat until the butter melts, stirring occasionally. Continue cooking for another 2-3 minutes while stirring constantly. The melted butter will start to foam on top, then will turn light brown in color and smell deliciously nutty. Remove from heat at this point and transfer to a glass container. Allow it to re-solidify for about 2-3 hours at room temperature or place it into the refrigerator for about 45 minutes. It should be completely room temperature and solidified (but easy to press a spatula into) before continuing on with the buttercream recipe.

When the brown butter has cooled to the ideal consistency, place it into the bowl of your stand mixer fitted with a paddle attachment (or use a large bowl and hand mixer) and add the cream cheese. Mix on medium-high until fluffy and light in color, about 5 minutes, scraping down the bowl and paddle as needed.

Turn the mixer to low speed and add the powdered sugar a few cups at a time, scraping down the bowl and paddle after mixing in each addition. Add the vanilla and salt and continue mixing on low speed until smooth and uniform. Use the frosting right away on cakes and cupcakes, or transfer it into an airtight container and store it in the refrigerator for up to two weeks.

Note: If you're ready to use the frosting and it seems too soft right after making it, refrigerate it for 20-30 minutes before remixing on low speed. This will help the butter in the recipe solidify a bit more to add stability.