Preheat the oven to 375°F and lightly grease a 9×13 baking dish.
Season and sear the chicken.
Heat avocado oil in a large skillet over medium-high heat. Season chicken generously with salt, pepper, and rosemary. Sear until golden on the outside (not fully cooked). Remove and set aside.
Sauté the vegetables.
In the same pan, add onions and carrots. Season lightly with salt and cook until softened, scraping up any browned bits from the pan.
Deglaze and build the sauce.
Add about ½ cup of the bone broth to deglaze the pan. In a bowl, whisk together remaining broth, milk, cottage cheese, and cornstarch. Pour into the skillet over medium-low heat and stir until thickened.
Combine filling.
Shred the chicken and return it to the pan along with the mixed vegetables. Stir until everything is evenly coated in the sauce.
Assemble.
Transfer the mixture to the prepared baking dish. Top with biscuits, spacing them evenly over the surface.
Bake.
Bake uncovered for 25–30 minutes, until the filling is bubbling and biscuits are golden brown.
Rest and serve.
Let rest for 10 minutes before serving to allow the sauce to fully set.