Preheat the oven to 350°F (175°C).
In a large mixing bowl, combine the sliced strawberries, ½ cup of granulated sugar, cornstarch, vanilla extract, and lemon juice. Mix gently and let sit for about 10 minutes to allow the strawberries to release their juices.
While the strawberries are resting, prepare the biscuit topping. In a medium mixing bowl, whisk together the flour, ½ cup of granulated sugar, baking powder, and salt.
Add the cold, cubed butter to the flour mixture. Use a pastry cutter or your fingers to work the butter into the flour until it resembles coarse crumbs.
Pour in the milk and ½ teaspoon of vanilla extract. Stir just until combined, being careful not to overmix.
Pour the strawberry mixture into a 9x13 inch baking dish and spread it evenly. Drop spoonfuls of the biscuit dough over the strawberry filling, leaving some gaps for the filling to bubble through.
Place the baking dish on a baking sheet to catch any drips, if necessary. Bake in the preheated oven for 45 minutes or until the biscuit topping is golden brown and the strawberries are bubbly.
Remove from the oven and let cool for about 10 minutes before serving. Enjoy warm, possibly with a scoop of vanilla ice cream!