With cooking spray, coat 2 baking sheets. In heavy, large saucepan, mix sugar, corn syrup and water. Cover; heat to boiling over high heat. Add butter; stir until butter is melted.Advertisement
Insert candy thermometer into sugar mixture. Over medium heat, cook, without stirring, 30 to 45 minutes or until mixture registers 305°F on candy thermometer.
Gradually stir in nuts and pumpkin seeds, keeping mixture from boiling. Remove from heat; add vanilla. Sprinkle baking soda over top; beat vigorously 15 seconds, being careful not to splatter the mixture.
Immediately pour onto prepared baking sheets; spread out evenly with metal spatula. Let cool. Break into large pieces. Store in airtight container at room temperature for up to 6 weeks.