First get out an 8 x 8 inch pan (or closest size you have) and grease it with separate butter from the 3 tbsp. canna butter. Next in a saucepan, mix together the cane sugar, chocolate pieces, half-and-half, corn syrup and 1.5 tbsp. of the canna butter. Turn burner on medium and begin stirring with a wooden spoon. Continue stirring until the chocolate has melted and the sugar has dissolved into the chocolate. After this is done increase the heat just a notch above medium. Bring to low boil. After it comes to a low boil, reduce the heat to medium-low, cover and return to a boil for an additional 2 to 3 minutes. Next remove the cover and attach a thermometer to the pot. Once it reaches a temperature of 234 degrees Fahrenheit, remove from the heat and add the remaining 1.5 tbsp. of canna butter. Just let the butter sit in the mixture and allow to cool for 8 to 10 minutes. Add vanilla and nuts, mixing thoroughly. Pour in the greased pan and allow to harden.