Line a 10 x 15-inch baking sheet with aluminum foil.  Butter the foil.  Spread with coarsely chopped nuts then set aside.  In a heavy 3-quart saucepan, combine butter, water corn syrup and sugar.  Place over high heat and stir constantly until mixture begins to thicken and turns to very light brown in color.  Reduce heat to medium-high and clip on a candy thermometer.  Cook until mixture reaches 290F (145C).  Remove from heat and carefully pour over chopped almonds in prepared baking sheet.

Let cool for exactly 12 minutes.  Lift toffee out onto a cutting board and score toffee to desired size and shape.  Let cool,  Break along score lines.  Cool completely.  Dip toffee into tempered chocolate then roll in chopped almonds.  Place on a baking sheet lined with waxed paper and cool until chocolate has hardened.  Store toffee in a cool location.  Can be made in advance and kept for at least 3 weeks.