Prepare a large bowl with an ice bath and set aside.
In a small pan over medium heat, add butter and melt. Once melted, toss in the sage.
Whisk butter continuously until the butter has browned. Keep an eye on it as this can happen quick!
Once the butter is brown, immediately transfer to a small bowl. Remove the sage leaves.
Whisk in onions, black pepper, and salt until incorporated.
Place small bowl with butter mixture over the large ice bath. Whisk butter mixture, constantly, until the butter becomes light in color and has a whipped consistency.
Enjoy!
Notes
*Make sure sage leaves are completely dry! Any moisture on them can make the butter pop while browning and it can get messy/hazardous lol