This cobbler is made in a cast-iron skillet right on the grill. It's packed full of juicy blueberries and flavored with lemon and thyme. Fresh herbs and sweets are a match made in heaven, and even better when you don't have to turn on your oven!
Prepare a grill for medium indirect heat. For gas grills (with 3 or more burners), turn all the burners to medium-low; after about 15 minutes, turn off the middle burner (you want the temperature to be 325 degrees F). For charcoal grills, bank one chimney starter full of lit and ash-covered briquettes to one side of the grill (be sure to consult the grill manufacturer's guide for best results).
For the filling: Combine the blueberries, granulated sugar, cornstarch, thyme and salt in a large bowl. Fold in the lemon zest, lemon juice and vanilla. Set aside while you make the biscuit dough.
For the biscuits: Whisk the flour, granulated sugar, baking soda, lemon zest and salt in a medium bowl. Work the butter into the flour with your fingertips until pea-size bits of butter remain. Use a rubber spatula to stir the buttermilk into the flour until the mixture comes together in a shaggy dough. (Don't overmix the dough.)
Pour the filling into a 10-inch cast-iron skillet. Tear the dough into 8 even pieces, flatten them slightly with your hands and then arrange them on top of the blueberries. Sprinkle the top of the biscuits with the turbinado sugar.
Put the skillet onto the indirect (no flame) side of the grill. Close the lid and cook until the biscuits are a golden and the filling is bubbling, 35 to 40 minutes. Let cool for 1 hour before serving.