Line a 13x9x2 baking pan with foil, extending foil over edges. Butter pan.
In a heavy 2-quart saucepan, cook butter and water over high heat to boiling. Add sugar. Reduce heat to medium; cook and stir till sugar is dissolved. Clip candy thermometer to side of pan. Continue cooking, stirring frequently, till thermometer registers 295 degrees (hard-crack stage). Remove from heat. Remove thermometer. Stir in 1/2 cup of the almonds.
Quickly pour candy into prepared pan; spread quickly and evenly. Slide foil and candy out of pan and onto countertop. Cover candy, using Topping Method 1 or II. Makes 1-1/4 pounds candy.
Sprinkle chopped chocolate over the top of the hot candy. When it's melted, spread chocolate over the candy. Sprinkle with remaining almonds. Cool candy; break into pieces.
Score candy into 2x2-inch pieces. Cut and separate pieces; cool till firm. Melt chocolate; spread on tops of pieces. Sprinkle with remaining almonds.
Be sure to use real butter in toffee. With margarine, the fat separates out onto the candy's surface.
