Gather all your ingredients: shredded chicken, frozen vegetables, cream of chicken soup, herbs, biscuit mix, milk, and melted butter.
In the slow cooker, combine the shredded chicken, frozen vegetables, cream of chicken soup, thyme, and black pepper. Stir everything together until evenly mixed.
Cover the slow cooker and cook on low for about 2 hours, stirring halfway through. The filling should be bubbling and thickened, with the vegetables tender.
While the filling cooks, prepare the biscuit topping. In a mixing bowl, whisk together the biscuit mix, cold milk, melted butter, and optional sage until just combined. The batter should be thick but scoopable.
Once the filling is ready, uncover and stir to ensure it's thick and bubbling. Then, spoon dollops of the biscuit batter evenly over the hot filling in the slow cooker.
Transfer the slow cooker insert to a preheated oven at 180°C (356°F). Bake uncovered for about 20-25 minutes until the biscuits are golden brown and flaky.
Remove from the oven and let the pot pie rest for about 5 minutes. The filling will thicken slightly and become even more flavorful.
Serve hot, with the flaky biscuit topping and hearty filling. Enjoy this cozy, stress-free comfort food!