Combine sugar, salt, water and butter in heavy 3-quart saucepan; heat to boiling on medium high heat. Add 3/4 cup almonds and cook, stirring constantly, to hard crack stage (300°-310°F.). Remove from heat. Stir in remaining 3/4 cup almonds, 1/2 cup walnuts and rum extract, mixing only enough to combine. Very quickly, pour into buttered jelly roll pan (15-1/2x10-1/2x1-inch) and spread evenly. Break chocolate bar into large pieces; place on warm toffee until melted, spread evenly, sprinkle with remaining 1/2 cup walnuts. When cool, break into pieces. Makes about 50 pieces. candy 10