1Line 15x10x1-inch pan with cooking parchment paper.
2In 12- or 14-inch cast iron skillet, beat sugar, water and vanilla paste with whisk. Stir in peanuts. Cook over medium heat, stirring occasionally, until mixture begins to boil rapidly, about 5 minutes. Cook, stirring constantly, until liquid reduces and sugar crystallizes on peanuts. Continue to cook and stir until peanuts are dry and crusty looking.
3Reduce heat to low; continue to cook and stir as sugar begins to turn to syrup and pool in bottom of skillet. Use spoon to continuously toss peanuts in syrup as it forms. Continue to do this until peanuts are golden brown, about 15 minutes.
4Sprinkle peanuts with cinnamon; toss to evenly distribute. Pour peanuts into pan; spread in single layer, breaking up any large clumps. Cool completely, about 1 hour. Store in an airtight container.