Using a double boiler, melt the chocolate in a medium size bowl. Add the milk and stir until the mixture thickens, approximately 5 minutes. Remove the bowl from heat and add the crumbs, salt, nuts, and vanilla and stir until well combined. Work quickly as the mixture will become stiff. Using a spoon, drop the mixture into rounded teaspoons onto a prepared greased cookie sheet. Place 1/2 a walnut on top of each cookie. Place cookies in oven and bake for 10 minutes. Remove cookies from oven and quickly transfer onto waxed paper to cool.