Heat oven to 350°F and adjust oven rack to middle position.

In a medium bowl, combine butter, mayonnaise, Parmesan, Fines Herbes and salt. Mix until fully incorporated.

Spread the butter/mayo mixture over the cut-side of each half of each bun, and place the buns cut-side up on a large rimmed baking sheet.

Bake 7 minutes at 350°F and rotate the baking sheet.

Set the oven to broil and cook the buns 1-2 minutes, or until the buns are golden brown and bubbly. Watch closely – the buns can burn easily.

Remove from the oven and cool 1 minute.

Serve hot and…

Enjoy!