Rhubarb Biscuit Cobbler

Preheat the oven to a high temperature of 400 degrees Fahrenheit (200 degrees Celsius).

Apply a thin layer of non-stick cooking spray to a 9-inch square baking dish.

To prepare the filling, combine granulated sugar and cornstarch in a large cooking vessel. Introduce rhubarb and water into the mixture, stirring until well combined. Bring the mixture to a rolling boil; cook and stir for 1 minute, allowing it to thicken. Transfer the filling to the prepared baking dish and top with small pieces of butter, sprinkling a pinch of ground cinnamon over the surface.

To create the topping, combine flour, 1 tablespoon granulated sugar, baking powder, and salt in a medium-sized mixing bowl. Use a pastry blender or two knives to break down the butter into small pieces, creating a mixture that resembles coarse crumbs. In a separate bowl, whisk together milk and egg until well combined; add this mixture to the flour mixture all at once, stirring gently until just moistened.

Drop spoonfuls of the topping over the rhubarb filling, followed by a sprinkle of the remaining 2 tablespoons granulated sugar.

Place the baking dish in the preheated oven and bake until the rhubarb is bubbling and the topping is crispy and lightly browned, approximately 20 minutes.