Heat oil in a pan until hot. Pour in wheat flour and turn down the heat. Stir frequently until flour turns golden. Remove from heat and let cool slightly. Add fine sugar, cinnamon and cardamom to flour and mix well.
Pour half of the flour-mix in a flat dish and flatten the surface with the back of a spoon. Insert a piece of walnut inside each date and place the dates on the flour-mix. Cover the dates with the rest of the flour-mix and again flatten the surface with the back of a spoon. Sprinkle ground pistachios on top. Cut into diamond-shaped pieces and serve.