Grease or butter a cookie sheet. Get out a medium saucepan, placing it over medium heat. Combine the canna butter, sugar and ice water in the saucepan heating for 12 - 14 minutes and stirring continually with a wooden spoon. Remove the spoon, ceasing to stir and allow to continue cooking until the mixture reaches 300 degrees on the candy thermometer. Remove from the heat once this temperature is reached, subsequently adding the nuts. Stir in the nuts, followed by the salt and vanilla extract. Pour onto the greased or buttered cookie sheet, until the mixture is roughly 1/4-inch tall. Before it cools, top with the chocolate chips, spreading as the chocolate begins to melt. Scatter the ice water on it, to break into chunks before it cools. Serve and enjoy. Store uneaten toffee in the freezer or refrigerator.