It's hard to believe that butter, sugar, and corn syrup can turn into the delectable candy we know and love as toffee. This crisp, buttery candy is coated with chocolate on the top and bottom.
Line a 15 x 10 x 1-inch jelly-roll pan with nonstick foil or regular foil coated with nonstick spray. In a medium-size saucepan, heat butter, sugar, corn syrup and 2 tablespoons water. Heat over medium heat to melt butter. Increase heat to medium-high and insert candy thermometer (see Note).
Cook mixture about 12 minutes until golden brown and temperature reaches 300°F. Do not stir. Remove from heat and remove thermometer. Carefully stir in 1 cup chopped almonds.
Quickly pour toffee onto prepared pan and spread to edges. Let stand in pan on a wire rack for 30 minutes.
Melt half of the chocolate in microwave on HIGH for 45 seconds; stir to smooth. Spread over top of cooled toffee; refrigerate 20 minutes until firm.
Once firm, flip entire bar over onto a sheet of waxed paper; remove foil. Microwave remaining chocolate on HIGH for 45 seconds. Stir until smooth. Spread over toffee bar; sprinkle with remaining 1/4 cup almonds. Use waxed paper to slide toffee bar back onto baking pan. Refrigerate 20 minutes more.
Once chocolate is firm, break bar into 2-1/2-inch pieces. Store airtight at room temperature, up to 1 month.