1 cup butter
1-1/4 cup sugar
2 tablespoons light corn syrup
2 tablespoons water
2 cups finely chopped toasted almonds
8 milk chocolate candy bars (1.55 ounces each)
Line a 13×9-in. pan with foil; set aside. Using part of the butter, grease the sides of a large heavy saucepan. Add remaining butter to the saucepan; melt over low heat. Add sugar, corn syrup, and water. Cook and stir over medium heat until a candy thermometer reads 300° (hard-crack stage).
Remove from the heat and stir in almonds. Quickly pour into the prepared pan, spreading to cover the bottom of the pan. Cool completely. Carefully invert pan to remove candy in 1 piece; remove foil.
Melt half of the chocolate in a double boiler or microwave-safe bowl; spread over top of candy. Let cool. Turn candy over and repeat with remaining chocolate; cool. Break into 2-in. pieces. Store in an airtight container.