Step #1 In the top of a double boiler over low heat/flame, melt the chocolate, stirring frequently until smooth.
Step #2 remove this from heat.
Step #3 With an electric mixer, 2-3 mins, cream the butter, sugar, eggs & vanilla extract until creamy & smooth, scraping the bowl every once in awhile.
Step #4 Slowly beat in the cooled chocolate until well mixed.
Step #5 slowly stir in the the flour & salt, stirring just until mixed.
Step #6 stir in the the pecans & sliced white chocolate.
Step #7 Cover the bowl with clingfilm & put in the fridge for 1 hr or until firm.
Step #8 Meanwhile, preheat the oven to 1900C/3750F/Gas 5.
Step #9 Lightly grease 2 large baking sheets.
Step #10 Drop rounded tsps of dough at least 5 cm/2" apart onto the prepared baking sheets, flattening slightly.
Step #11 Bake for 8-10 mins, or just until the surface feels slightly firm when touched with a fingertip.
Step #12 Remove the baking sheets to wire racks to cool for 5-7 mins.
Step #13 With a palette knife, remove the biscuits to a wire rack to cool completely.
Step #14 Repeat with the remaining dough.
Step #15 When cool drizzle the chocolate over them using a spoon.