Line an 8x8" baking pan with wax paper then set aside.
Combine the white chocolate, butter, salt and sweetened condensed milk in a pot over medium heat. Stir until smooth then stir in the instant pudding mix until combined. Once combined add the marshmallow fluff and stir until melted and smooth.
Pour into the prepared pan and top with the pecans (you can chop the pecans before adding on top or place whole pecans on top). Let cool for at least 1 hour or until set.
Once cool, carefully pull out of pan and cut into 1 inch squares. Melt the chocolates according to package instructions and dip the bottoms of the fudge squares into the chocolate, then place on a sheet of wax paper to cool. Use any leftover melted chocolates to drizzle on top of the pecans.