THAW DOUGH. Thaw biscuit dough under refrigeration according to manufacturer directions.
PREPARE FRUIT. Place peaches and all packing liquid in a steam-table/hotel pan. Roughly chop peaches as needed. Do not drain.
MAKE SLURRY. Remove approximately 1 cup liquid from the peaches. Whisk with 1 cup cornstarch until completely smooth and free of lumps.
COMBINE. Stir slurry, brown sugar, and cinnamon thoroughly into peaches and remaining liquid.
OVEN-COOK FILLING. Bake in 350 degree oven, stirring periodically and scraping the bottom and corners of the pan, until bubbling and thickened. Stir in vanilla after cooking. OBSERVABLE STANDARD: Filling should reach a pie-filling consistency: thick and spoonable, able to hold its shape when portioned, and not watery or runny. Properly thickened filling helps prevent leaking during assembly and baking.
COOL FILLING. Cool before assembly. Do not fill dough with hot filling; it should be cool enough that it does not soften the dough or make it difficult to handle and seal.
SHAPE DOUGH. On a lightly floured surface or parchment-lined sheet pan, roll or press each biscuit into an approximately 5 x 6-inchrectangle. Keep dough cool while working.
FILL. Using a #12 disher, portion approximately 1/3cup filling onto one side of each dough rectangle. Leave a clean border around the filling.
FOLD & SEAL. Fold dough over filling to form a rectangle or half-moon. Press edges firmly together; seal with a fork as needed. Edges should be completely sealed with no filling caught between dough surfaces.
PAN & VENT. Place on lightly sprayed, parchment-lined sheet pans. Cut or poke 2 small vents in the top of each pastry.
BAKE. Bake at350°F convection for approximately 14-18 minutes, rotating pans as needed. Pastries should be evenly golden brown and fully baked with no raw or gummy dough.
SERVE. Cool slightly before serving. CAUTION: Fruit filling may remain very hot after the exterior pastry has cooled.