In a heavy bottom pot melt the sugar, butter and water over high heat. Constantly stirring mixture until it comes to a full boil. Continue boiling and stirring until it reaches 310 degrees on a candy thermometer or it reaches a hard crack stage when tested in a cup of cool water. This wil take about 30-35 to reach this stage- the color will look like caramel. Remove from heat and carefully add vailla extract. Stir to mix in vaniila. Pour mixture into the prepared 11 x 17 pan. Let cool for 10-15 minutes then top with chocolate chips. Allow them to melt slightly and spread over surface of toffee. You can add chopped nuts also. I like prefer not to add nuts but sprinkle with a bit of sea salt to bring out the flavor of the chocolate.
Enjoy. Keep loosely covered in pan or you can break it up into pieces and store in a tightly sealed container.