In a medium sized heavy saucepan melt the butter over low to medium heat stirring occasionally to keep from browning.
While the butter is melting lightly butter a large 12 x 17 cookie sheet.
Hang a candy thermometer on the inside of the pot while cooking, make sure it does not rest on the bottom of the pan.
Once the butter is melted add the sugar, corn syrup, and water.Stir and mix to a sugary goo.
Raise heat to medium or medium-high (the higher the heat the faster you need to be prepared to stir)
Stir using a wooden or non heat-conducting spoon at a slow pace taking brief breaks until the temp is approximately 225 degrees. (The only reason for stirring slow is to save your energy for the latter stages)
Above 225 degrees, stir constantly and progressively more quickly to minimize scorching. (The hotter the stove top, the more prone the mix is to burn)
After the heat rises above 270 degrees watch carefully because it will begin to heat up more quickly.
Toward the end, you will feel like both the toffee and your arms are burning. (20-30 minutes) By now you will have switched hands several times. You will want to stop. Keep going! Toward this end it will have turned a dark golden brown and may be smoking a bit.
After the temperature passes 290 degrees, remove from heat, stir in the coarse nuts, and remove the thermometer. (A little burning on the bottom of the pan is normal. A lot of burning may not ruin it, but might add a slightly bitter taste making it more suitable to ice cream topping. Well yes, you can over cook and burn it if you try hard and don’t stir enough.)
Pour entire mixture onto the cookie sheet, spreading evenly to the edges with the stirring spoon.
After cooling slightly, (5-10 minutes) spread the chocolate chips evenly over the surface. Wait a few minutes to allow the chips to melt. (If you allowed it to cool too much a hair dryer can assist in melting the chips.) Avoid smearing the chips all the way to the edge of the pan to simplify cleaning.
Once the chocolate is spread, sprinkle the finely chopped nuts across the surface. (Optionally, press surface with a clean dry hand to assure nuts are stuck tight.)