Butter.

The French would be the first to tell you that to avoid butter is to shy away from the heart and soul of baking. There's not a whole lot you can do without butter. None of this margarine stuff, it doesn't ever freeze so the dough is perpetually squishy, which is odd and makes it difficult to roll out. 
Shortbread is one of those things whose very existence depends on this magical compound - no eggs, no leavening agent, no nothing. If you're not a college student whose food budget would probably be better spent on things like broccoli and lettuce, I advise splurging for fancy European-style butter because the finished product will be fantastic!

In order to spice this recipe up, I decided to infuse the butter with loose tea leaves I imported from the most famous fine tea maker in Paris, Mariage Freres. The flavor is called "Pleine Lune" (or "Full Moon" for you non-francophones) and it's a black tea with hints of vanilla and almond. Sounds fancy huh? You can even do this with any kind of tea - try Earl Grey, English Breakfast, Chamomile, etc.

Although "infusion" evokes images of all kinds of baking voodoo, it basically means melting the butter, stirring the tea leaves in and s them steep for a little, so you get the lovely mixture you see at right. Then so you don't eat potpourri, strain out the leaves. It's better to have pretty strongly flavored butter, so put in one tea bag per stick of butter. Let the butter solidify reasonably in the freezer or fridge before you cream it with the sugar in the recipe.

Shortbread Cookies 

Yields about 24 cookies (depending on size)

Recipe adapted from Joy of Baking

2 C all-purpose flour

1/4 tsp salt

1 C (2 sticks) unsalted butter (infused with 2 bags of tea of your choice), at room temperature

1/2 C powdered sugar

1 tsp vanilla extract

Directions: Cream butter and sugar in a mixing bowl with an electric mixer until smooth (about 2 min). Beat in vanilla extract. Gently stir in the flour and salt until just incorporated (knead with your hands if necessary). You may need a little less flour than called for because you lose a little butter when you strain the tea leaves out. If that's the case, melt some butter and sprinkle it on the dough to make it stick together more. Flatten dough into a disc, wrap in plastic and refrigerate until stiff.
Preheat oven to 350 and line baking sheets with parchment. Roll out dough to 1/4 inch thick and cut with cookie cutters. Bake for 7-9 minutes or until just browned (no one likes a burned cookie!). Cool on a rack. Eat with tea.