Preheat your oven to 375°F / 190°C.
In a medium saucepan, combine the diced rhubarb, honey, cornstarch, orange zest, cinnamon, and cloves.
Cook over medium heat, stirring occasionally, until the rhubarb is tender but still holds its shape, about 10 minutes.
Remove the pan from the heat and stir in the butter until it's fully melted.
Pour this gorgeous, fragrant filling into an 8x8-inch (20x20 cm) baking pan.
To make the biscuit topping, whisk together the flour, sugar, baking powder, and cinnamon in a large bowl.
Cut the chilled butter into the flour mixture using a pastry blender or your fingertips until it resembles coarse crumbs.
Pour in the cold milk and stir with a fork just until a shaggy dough forms. Be careful not to overmix!
Turn the dough onto a lightly floured surface and gently knead 3 or 4 times, just enough to bring it together.
Roll it out to an 8x8-inch square.
Carefully lay the biscuit dough over the hot rhubarb filling.
Brush the top with the beaten egg for a beautiful golden finish.
Bake for 30 minutes, or until the topping is golden brown and the filling is bubbling up the sides. If the top browns too quickly, cover it loosely with foil.
Let the cobbler cool for at least 15 minutes before serving. This allows the filling to set up a bit.
Serve warm with a generous dollop of whipped cream.
Keep it Cold: For the flakiest biscuit topping, make sure your butter and milk are very cold. This creates steam pockets as it bakes, resulting in a light, tender texture.
Don't Overwork the Dough: Mix the biscuit dough just until it comes together. Overworking develops gluten, which will make your topping tough instead of tender and fluffy.
Don't Overcook the Filling: On the stovetop, cook the rhubarb just until it's tender-crisp. It will continue to soften in the oven, and this prevents it from turning into complete mush.
