Line a 13-by-9 inch baking pan with foil, extending foil over the edges. Sprinkle almonds on the bottom of pan. Butter sides of a heavy 2-quart saucepan.
Melt butter over low heat. Stir in sugar, water and corn syrup. Cook and stir over medium-high heat to boiling.
Clip candy thermometer to side of pan. Cook over medium heat, stirring frequently, until thermometer reads 290 degrees (soft-crack stage). Watch carefully after mixture reaches 280 degrees.
Remove pan from heat. Pour mixture into prepared pan. Let stand 2 or 3 minutes, until surface is firm. Sprinkle with chocolate pieces. Let stand 1 to 2 minutes, until chocolate chips are glossy and soft.
Spread evenly over candy. Chill until firm. Lift candy out of pan with foil; break into pieces. Makes about 1 1/2 pounds.