Heat the oven to the lowest setting. Line a large baking sheet with parchment or a silicone mat and place it in the oven to warm.
Stir together the sugar and syrup in a large glass bowl and microwave for 3 minutes. Stir again and cook an additional 3 minutes. Stir in butter as it melts and then stir in the peanuts. Cook an additional 2 minutes. Stir in the vanilla and baking soda.
Quickly pour the mixture onto the lined baking sheet. Spread the candy as flat as possible with a spatula. (Lightly buttering the spatula will help make it easier to spread.) Let the candy sit at room temperature until it hardens, about 20-30 minutes. Break into pieces and store in an airtight container at room temperature for 2-3 weeks. Enjoy!