Remove one sixteen-ounce package frozen mixed berries from freezer and allow to thaw at room temperature for approximately ten to fifteen minutes ensuring only superficial softening while keeping most berries solid and intact.

Preheat oven to exactly three hundred seventy-five degrees Fahrenheit using an oven thermometer to verify true temperature as many home ovens run fifteen to twenty-five degrees off from dial settings.

Pour partially thawed berries into a ten to twelve inch cast-iron skillet creating an even single-layer bed of fruit.

Sprinkle one and one-half tablespoons granulated white sugar evenly over the berry bed allowing the sugar crystals to draw juice from the fruit through osmotic maceration creating a pectin-rich juice base.

Remove refrigerated sugar cookie dough from refrigerator allowing it to sit at room temperature for approximately five minutes until pliable.

Tear or cut cookie dough into irregular pieces approximately two to three inches across creating rustic, non-uniform shapes with varied browning patterns.

Arrange cookie dough pieces over the berry base leaving visible gaps of approximately one inch between pieces to allow steam venting and syrup bubbling.

Sprinkle remaining one and one-half tablespoons granulated sugar evenly over the top of cookie dough pieces creating a craggy sweet crust.

Place cast-iron skillet into preheated three hundred seventy-five degree Fahrenheit oven and bake undisturbed for approximately thirty-five to forty minutes.

At the twenty-five minute mark briefly check cobbler progress by opening oven door observing browning level and syrup bubbling at edges adjusting temperature if necessary.

Continue baking until cookie dough pieces show deep golden-brown crust and syrup is visibly thick and bubbling with a thin knife inserted into thickest dough piece emerging clean or with just a few moist crumbs.

Remove cast-iron skillet carefully from oven using oven mitts as handle will be extremely hot and berry syrup remains molten and hot.

Allow cobbler to rest in pan for approximately ten to fifteen minutes permitting pectin to continue cross-linking slightly and cookie dough crumb to set more firmly as starch cools.

Serve cobbler directly from cast-iron skillet using a spoon allowing each person to scoop a cookie piece with generous spoonful of glossy berry syrup.

Best served warm ideally within thirty minutes of removal from oven while cookie texture remains crisp and syrup remains at optimal thickness.