Cream the butter until light and fluffy in a medium-sized bowl. Add flour, Parmesan, spruce tips and salt and mix thoroughly until the dough starts to clump together.

Transfer dough to a work surface and press and pat it into a disc. Divide the disc in half. 

Taking the first half, shape the dough into a squared log of about 1 1/2 inches in diameter and 6 inches in length, pressing firmly. Press the ends down on the counter to flatten them. 

Repeat with the second half of the dough. Wrap each one tightly in plastic or waxed paper, twisting the ends, and refrigerate for a good hour. 

Preheat the oven to 350F about 15 minutes before you plan to bake, and line two baking sheets with parchment paper. 

Cut each log into 1/4-inch slices—you should be able to get 12 slices from each one.

Arrange on a baking sheet about an inch apart. Bake for 15 to 18 minutes, until shortbreads are just turning golden at the edges.

Remove from oven and cool shortbreads on a rack; as they cool, the sprucey flavour becomes more pronounced. 

Serve with eggnog, on a cheese platter, or with a quiet Rob Roy cocktail sipped while gazing out the window at falling snow.