Squeeze the orange and reduce the juice to a syrup with 3 lightly heaped tablespoons of sugar. Let cool down.
Beat the soft butter and sugar in a bowl until frothy. Fold in 2 tablespoons of the orange syrup and the flour. Mix everything until all ingredients are well mixed. Knead with your hands until you get a firm dough.
For the filling, mix the walnuts, cinnamon and the remaining orange syrup.
Roll a heaped teaspoon of dough into a ball and press a well in the middle with your thumb. Add 1 teaspoon of the filling.
Grease a baking sheet, put parchment paper on top and grease too. Place the cookies on the baking sheet and gently flatten them a little.
Bake in a preheated oven at 160 ° C for about 15-20 minutes (until golden brown).