1 Preheat the oven to 350°F.
2 In a large bowl, beat the butter with the icing sugar until fluffy; beat in the vanilla.
3 In a separate bowl, whisk together the flour, ginger and salt; stir into the butter mixture just until the ingredients are combined and come together to form a dough.
4 Shape the dough into thirty-six 1" balls.*
5 Arrange 1" apart on parchment paper-lined baking sheets. Press your thumb into the centre of each ball, leaving an indentation; pinch together any cracks around the edges.
6 Bake until the edges of the cookies are golden, about 12 minutes. Let the cookies cool on the sheets for 3 minutes, then transfer to racks to cool completely.
7 When the cookies are cool, spoon a scant 1 teaspoon of filling into the well of each one.
*To roll the cookies in nuts, whisk 2 egg whites with 1 teaspoon water until frothy; place finely chopped nuts (such as pistachios, walnuts or hazelnuts) in a bowl. Using a fork, dip each dough ball into the egg mixture, then into the nuts to coat. Place on the prepared baking sheets and continue with the recipe as directed. To dust with cocoa or cinnamon, roll the dough balls into either cinnamon or cocoa powder, shaking off any excess. Place on the prepared baking sheets and continue with the recipe as directed.
Makes: 3 dozen cookies