• Set oven to broil. Place slivered, peeled almonds on baking sheet and place under broiler until golden brown, about 3 to 4 minutes. Watch closely so they do not burn. Allow to cool, then roughly chop. Set aside for topping.
• Butter a 10-by-15-inch baking tray. Set aside.
• Place butter in a heavy bottomed, 2-quart saucepan over medium heat. Heat butter until just melted, about 2 to 3 minutes. Add the sugar, stir until combined about 2 minutes, then add the whole almonds. Continue to gently stir, folding mixture and scraping sides, over medium heat, for 16 to 20 minutes. The mixture starts out light, thick, and grainy, and as it cooks, it gradually darkens in color then bubbles and begins to thin and look silky. As the color darkens, keep stirring carefully and measure the temperature with a candy thermometer.
• Once the mixture reaches 310 to 315 degrees F, turn off heat and immediately add vanilla extract. The vanilla will cause the mixture to bubble rapidly. Quickly, fully mix in vanilla, then carefully pour toffee onto the buttered baking tray. Quickly, run a large offset palette knife or rubber spatula over the top, evenly spreading toffee making sure nuts are distributed throughout. Allow to cool.

CAUTION: Hot toffee will burn so use care not to splash or get it on skin!

• Using a double boiler, melt ½ of the chocolate chips. Spread melted chocolate over the top of cooled, hardened toffee and top with ½ the toasted almonds. Allow to cool. Flip toffee over and repeat process again with remaining chocolate and almonds. Again, allow chocolate to cool, then break into pieces. Store in air tight container.