Butter, or line a 11x18 cookie sheet.

Chop nuts and spread 2 cups over buttered sheet.

Put butter, water and sugar in saucepan and cook over medium high heat stirring constantly until 300 degrees f or crackled stage on thermometer.

Remove from heat, add vanilla and stir.

Spread mixture on sheet over pumpkin seeds.

Sprinkle chocolate chunks over hot toffee and let them melt for 5 minutes.

Once the chocolate has started to melt, spread with an offset spatula and sprinkle with remaining pumpkin seeds.

Allow the toffee to cool and harden for 4 hours at room temperature or stick in the refrigerator for 30 minutes.

Break apart and store in an air tight container for up to two weeks.