Butter a large baking sheet; set the baking sheet aside. In a small saucepan melt 1 Tbsp. butter over low heat. Stir in the chopped peanuts, pepitas, and crushed red pepper; keep warm over low heat.
To caramelize the sugar, in a heavy 10-inch skillet heat sugar over medium heat until sugar begins to melt, shaking skillet occasionally to heat sugar evenly. Do not stir until sugar starts to melt. Once sugar starts to melt, reduce heat to low. Stir occasionally with a wooden spoon, gradually incorporating the unmelted sugar into the melted sugar until all is melted and golden brown. Reduce heat if syrup browns too rapidly before all the sugar melts, about 12 to 15 minutes.
Remove the skillet from the heat; quickly stir in the warm nut mixture. Immediately pour the mixture onto the prepared baking sheet.
If desired, working quickly, stretch the candy by using two forks to lift and pull the candy as it cools. Pull gently to avoid tearing the candy (candy will set up quickly). Cool completely. Break the candy into pieces. Store tightly covered.