Preheat oven to 375°F. Dissolve coffee in boiling water. Set aside to cool.

Cream margarine and sugar in a large mixing bowl. In a separate bowl, sift together dry ingredients. Add flour mixture to creamed mixture, along with the dissolved coffee. 

Spoon mixture into a pastry bag, fitted with a plain nozzle or a tip with a large opening. Pipe 2 to 2 1⁄2inch swirls, slightly apart on 3-4 lined baking sheets. 

Bake for 10 to 15 minutes until firm, but not browned. Allow to cool. Place cooled cookies close together.

Melt white chocolate with oil and dark chocolate separately. Using a teaspoon, take some white chocolate and flick it over the cookies, moving your hand speedily from left to right to create small lines of drizzle. When all of the white chocolate has been used up, turn the cookies 90 degrees. Flick the dark chocolate over the cookies so that the dark chocolate is at an opposite angle to the white chocolate. Allow cookies to sit until chocolate has set; then remove from paper.