Sift the flour and salt together in a bowl and set aside. Mix the butter and date paste in a mixer on medium speed until light and fluffy (about 2 min.) Add the egg and vanilla and mix until incorporated.
While the mixer runs on its lowest speed, gradually add the flour and mix until just blended and a dough ball forms. Scrape down the sides of the bowl, cover with plastic wrap and refrigerate for at least one hour.
Using a small biscuit scoop or a tbsp. to measure, roll the dough into balls. Roll the balls in the chopped walnuts and place on parchment-lined baking trays at least 5 cm apart. Using your thumb, make an indentation in the middle of each of the biscuits. Refrigerate for 20 minutes.
Bake for 15-20 minutes or until very lightly brown. While still warm, gently press a chocolate kiss into the indentation.
Allow the biscuits to cool completely on a wire rack.
Vanilla Medjool Date Balls
