--(imported), finely chopped Butter small cookie sheet. Melt butter in heavy 2-1/2 quart saucepan over low heat. Add both sugars, water, molasses, espresso, cinnamon and salt; stir until sugar dissolves. Attach clip-on candy thermometer to pan. Increase heat to medium; cook until thermometer registers 290 degrees F, stirring slowly but constantly and scraping bottom of pan with wooden spatula, about 20 minutes. Remove pan from heat. Mix in 1-1/2 cups nuts. Immediately pour mixture onto prepared sheet; do not scrape pan. Tilt sheet so that toffee spreads to 1/4-inch thickness. Sprinkle chocolate by generous tablespoons atop toffee, alternating bittersweet and white chocolates. Let stand 1 minute. Using back of spoon, swirl chocolates to spread slightly. Shake sheet to form even chocolate layer. Using tip of knife, swirl chocolates to create marble pattern. Sprinkle with remaining 1/2 cup nuts. Refrigerate until toffee is firm, about 1 hour. Break toffee into pieces. (Can be made 2 weeks ahead. Chill in airtight container.) Serve cold or at room temperature. Yields 2 pounds *