Grease an 8 x 8 inch baking pan with baking spray or butter and set aside.
In a large bowl mix sugar with salt and set aside.
Add butter to a small saucepan and melt over medium high heat until browned and fragrant. The butter will turn a deep golden brown color, this may take 3-4 minutes. Stir continuously and remove from heat when golden brown.
Pour the butter over the salt and sugar, mix until combined. Whisk in the egg and mix until combined.
Using a spatula, stir in the flour and mix just until incorporated. The dough will be very thick, almost like play dough. This is ok, if needed use your hands to incorporate last bits of flour.
Divide the dough in half, and press half of the dough into the bottom of the greased pan. Top with Dulce de Leche, followed by coconut and walnuts. Crumble on top the remaining dough, pressing it slightly.
Bake for 25-30 minutes, or until the top is golden brown.