Line a standard rimmed baking sheet with foil and spray with non-stick cooking spray; set aside.

Using a medium saucepan, add butter and place over medium-low heat. Stir occasionally with a wooden spoon until butter has completely melted.

Place candy thermometer in saucepan. Add sugar, increase heat to high and stir. Continue heating, stirring constantly, until temperature reaches 300°F. (Note: This could take 10-15 minutes. Continue stirring to prevent butter/sugar mixture from burning.) (Note2: Use a large saucepan than you think you need. The butter/sugar mixture will expand as it heats!)

Pour butter/sugar mixture into prepared baking sheet; spread mixture evenly with a wooden spoon. Let mixture cool at room temperature for 15 minutes.

Meanwhile, spread chopped almonds on a baking sheet and bake at 350°F for 3-4 minutes. Shake pan and then continue toasting for another 1-2 minutes. Set almonds aside. (Note: Watch almonds closely when toasting as they can burn quickly!)

Using a double-boiler or a microwave, melt chocolate chips until fully melted. Pour chocolate over butter/sugar mixture and spread evenly. Sprinkle toasted almonds evenly on top of chocolate.

Let toffee cool completely and then cut with knife or break into rustic pieces.