Place your flour, sugar, and salt in a large bowl and whisk to combine.

Cut your butter into small cubes (½-inch is ideal here) and add them into the flour mixture. Toss them around so that they’re coated and used your fingers to squash each butter cube into flatter, lima-bean like pieces. It’s totally fine if this is bigger than you’re used to.

Pour water over butter-flour mixture and use a flexible silicone spatula or scraper to bring it together into a dough that will seem too wet and sticky, but will be just fine. Divide dough into two parts, and wrap each half into flat-ish packets wrapped in plastic, waxed or parchment paper.

Chill in the fridge until firm — one to two hours.

Preheat oven to 400°F. Line a rimmed baking sheet with parchment paper, set aside. Lightly grease an 8 or 9-inch casserole dish or oven-proof skillet with vegetable cooking spray. Set aside.

In a medium saucepan mix together 1 cup of sugar, cornstarch and boiling water. Bring the sugar mixture to a boil over medium heat. Boil 5 minutes stirring occasionally until thickened. Remove from the heat and add the blackberries and any accumulated juice. Stir gently until the blackberries release some juice. Set aside.

Cut one of the pastry disks in half and roll out on a lightly floured surface to about ⅛th inch thick. Cut the pastry into a square roughly the same size as the prepared pan. Reserve any pastry scraps. Place the pastry square on the parchment lined baking sheet and bake until firm, lightly browned with bubbles starting to form on the crust, about 10 minutes. This will be used for the middle layer of the cobbler. Set aside.

While the pastry square is baking, roll out the remaining whole disk of dough to at least a 12x12-inch square, about ⅛ inch thick. Gently ease the dough into the prepared dish pressing gently into the corners without stretching. Trim the edges of the dough leaving a ½-inch overhang all the way around. This overhang will be folded up and over the lattice top. Collect any scraps of dough and put them together with the remaining ½ disc of pastry.

Spoon half the blackberry mixture into the prepared pan. Top with the pre-baked pastry square, then add all the remaining blackberry mixture. Dot the blackberries with butter.

Roll out the remaining dough to a 10-inch square (for 9-inch pan). Cut the dough into 8 or 10 strips and weave a lattice crust on top. Trim the excess dough to the same size as the overhang. Lightly dampen the top and bottom edges of the dough strips with a wet finger. Fold the excess overhang up and over the edges of the strips to seal. Crimp or seal the edges with a fork.

Place the baking pan on the parchment lined baking sheet to catch any juice that may bubble over. Bake at 400°F for 10 minutes then reduce the heat to 350°F and continue baking for about 45 to 55 minutes or until the crust is golden brown and the juices are bubbling. If the crust is browning too quickly, tent the cobbler with foil as needed.

Cool to room temperature or serve warm topped with ice cream or lightly sweeten cream if desired.