Simmer Chardonnay until reduced by half, add sugar and simmer for 15 more minutes. Remove from heat.
Peel and slice peaches. Pour Chardonnay syrup over peaches and toss together with flour.
On a lightly floured surface, roll out puff pastry to 1/4-inch thick.
Cut circles with a large cutter (I like to use the fluted edge of a 5-inch fluted tart shell).
Place a generous spoonful of peaches into centre of each puff disc. Dot each with butter, baste edges with water, fold in half and crimp edges together. Place on a parchment-lined baking sheet and chill for 20 minutes before baking.
Preheat oven to 375 F.
Brush turnovers with eggwash.
Combine turbinado sugar and cinnamon and sprinkle on top. Make a few little snips with a pair of scissors to allow steam to escape.
Bake for 20 minutes.
Serve warm or at room temperature.