• Combine mashed banana, buttermilk and vanilla in a large measuring cup and place in the refrigerator until read to use.
• Add flour, sugar, baking powder, baking soda and salt to the bowl of a food processor and process to mix. Add cold cubed butter and process until the butter is pea size. Add nuts and process until combined.
• Add the buttermilk mixture and process until it just comes together. Dump it out on to a floured cutting board and form into a rectangle. Cut the rectangle into thirds and stack them on top of each other. Pat it down into a rectangle and repeat two more times.
• Roll the dough into a 10 x 4 inch rectangle about 1 inch thick. Cut it crosswise into 4 equal rectangles cut each rectangle in half forming two triangles. Place on a parchment lined baking sheet and freeze for 30 minutes.
• Preheat oven to 400º.
• In a small bowl whisk the egg with a tablespoon of buttermilk and brush over the top of the scones.
• Bake for 20-25 minutes until golden brown.

Frosting

• Add the butter to a light colored saucepan and melt over medium-high heat, whisking occasionally. It will first melt then foam up. Once it begins to brown, watch it very closely then remove once it has turned an amber color and immediately remove from the saucepan to a glass bowl or measuring cup. Refrigerate until slightly solid.
• In the bowl of an electric mixer, add the solid brown butter that is slightly soft with the cream cheese and beat on high speed until creamy and smooth. Add vanilla and salt and mix to combine. Gradually add the powdered sugar and beat on low speed so that it doesn’t fly out of the bowl. Once incorporated, beat on high until smooth and creamy.