This fruity dessert featuring sweet, tart blueberries and a flaky biscuit topping is sure to turn you into a cobbler gobbler!
For the filling: Adjust oven rack to middle position and heat oven to 375 degrees. Line rimmed baking sheet with parchment paper.
In large bowl, use rubber spatula to stir together cornstarch, lemon zest, pinch salt, and ¾ cup sugar. Add blueberries and lemon juice and gently toss to coat.
Use rubber spatula to scrape mixture into 8-inch square baking dish. Place baking dish on parchment-lined baking sheet. Place baking sheet in oven. Bake until filling is hot and starting to bubble around edges, about 25 minutes.
For the biscuit topping: While filling bakes, in second large bowl, whisk together flour, baking powder, baking soda, ½ teaspoon salt, and remaining 1 tablespoon sugar. In liquid measuring cup, use fork to stir buttermilk and melted butter until butter forms small clumps.
When filling is ready, use oven mitts to remove baking sheet from oven (ask an adult for help). Place baking sheet on cooling rack. Increase oven temperature to 475 degrees and let filling cool for 10 minutes.
Add buttermilk mixture to bowl with flour mixture. Use clean rubber spatula to stir until just combined.
Use oven mitts to return baking dish (still on baking sheet) to oven. Bake until biscuits are golden brown and toothpick inserted in center of 1 biscuit comes out clean, 12 to 14 minutes.
We bake the berry filling before topping the cobbler with the biscuit dough. Then we bake it again to get our fluffy, flaky biscuits. This works so well because if the berry filling is hot when the biscuit dough is put on top, it helps cook the biscuits from the bottom while the heat from the oven cooks the top.