Start with preheating oven to 300°F/150°C/Gas Mark 2.
Add butter to a small skillet, let melt over medium heat. Continue heating and stirring until begins to brown. It will take about 6 minutes, but make sure it does not burn. Use a fine sieve to strain browned butter into a small bowl, cover and chill for 30 minutes until sets to firm.
Beat chilled butter with powdered sugar using an electric mixer on medium-high speed for about 2 minutes. The mixture should become creamy and paler in color.
Turn the mixer speed down to low; beat in sifted flour and salt until just blended. Make sure you do not overbeat.
Line the working surface with paper parchment. Place dough on parchment, top with another sheet of parchment and roll out keeping a rectangular shape to a thickness of 1/2 inch.
Remove top parchment sheet. Transfer the dough onto a rimmed baking sheet together with the bottom sheet of parchment.
Pierce the dough rectangle with a fork at 1-in intervals. Bake for 30 minutes, rotate, bake for 30 minutes more until firm and golden-brown.
Cut into strips and then crosswise into thirds while still warm. Set aside to cool to room temperature.