Melt butter, 4 teaspoons dried sage and orange peel in small saucepan over medium heat.
Stirring, cook until butter begins to brown.
Strain into bowl of stand mixer fitted with the paddle attachment and allow to cool to room temperature. Once cool, beat butter for about 1 minute. Add powdered sugar and continue to beat until fluffy and lemony yellow, about 2 minutes, occasionally scraping the sides of bowl. Beat in vanilla.
Whisk together flour and salt. Add flour mixture and mix on low speed, scraping sides if necessary, until flour is just incorporated and dough sticks together when squeezed with fingers.
Using your hands, roll cookie dough into a 10-inch-long log (about 3 inches in diameter).
Wrap in plastic wrap and chill in refrigerator for at least one hour.
While dough chills, combine sugar and 1 teaspoon of dried sage leaves in a bowl and press through a strainer to break up the sage. Set aside. Preheat oven to 350 degrees.
Once cold, cut the log into twenty 1/2-inch-thick disks. Place disks on parchment-lined cookie sheet. Sprinkle with sage sugar. If desired, press a small, fresh sage leaf onto the top of each cookie.
Bake for 15 minutes or until lightly browned around the edges. Remove from pan and let cool completely on a wire rack. Cookies can be stored at room temperature in airtight container for up to one month.