Step 1Melt unsweetened chocolate, 1 1/2 cups chocolate chips and butter in top of double boiler set over, but not touching, simmering water. Stir occasionally until mixture is smooth and completely blended. Set aside to cool to room temperature.
Step 2Sift together flour, baking powder and salt in medium mixing bowl. Set aside.
Step 3Combine eggs, sugar, espresso powder and vanilla in large mixing bowl and beat at medium speed until mixture holds a ribbon when beater is lifted away, about 4 minutes. Fold in cooled chocolate mixture. Sift half flour mixture over top and fold it in gently.
Step 4Repeat with remaining flour mixture. Fold in remaining chocolate chips and macadamia nuts. Cover batter and chill in refrigerator 30 minutes.
Step 5Grease and flour 2 large baking sheets. For each cookie, spoon about 2 tablespoons batter onto baking sheets, placing cookies at least 1 inch apart and making sure nuts are evenly distributed.
Step 6Bake at 400 degrees until cookies are puffy and shiny, 7 to 10 minutes. Cool on wire rack. Serve warm or at room temperature.