Prep the pan and oven: Preheat your oven to 375°F (190°C). Lightly spray a standard 12-cup muffin tin with nonstick spray.
Sauté the aromatics: In a large skillet over medium heat, melt the butter with the olive oil.
Add the onion and cook 3–4 minutes until softened. Stir in the garlic and cook 30 seconds until fragrant.
Build the filling base: Sprinkle the flour over the onions and stir to coat. Cook 1 minute to remove the raw flour taste.
Add liquids: Slowly whisk in the chicken broth, breaking up any lumps.
Stir in the milk. Simmer 2–3 minutes until the mixture thickens into a light gravy.
Season and fold in the good stuff: Add thyme, parsley, salt, pepper, and optional poultry seasoning. Stir in the thawed vegetables and chicken.
Simmer 1–2 minutes, then remove from heat. Taste and adjust salt and pepper. The filling should be creamy but scoopable.
Prep the biscuits: Separate the biscuit dough.
For large biscuits, split each in half horizontally to make two thinner rounds. For smaller biscuits, use as is. Gently press each piece into a muffin cup, pushing up the sides to form a little dough “cup.”
Fill them up: Spoon the chicken mixture into each biscuit cup, filling almost to the top.
Don’t overfill or it may bubble over.
Bake: Place the muffin tin on a sheet pan to catch any drips. Bake 14–18 minutes, until the biscuit edges are deep golden and the centers are bubbly. Rotate the pan halfway through for even browning.
Rest and release: Let the bites cool in the pan for 5 minutes to set.
Run a small offset spatula or butter knife around each one and lift out gently.
Serve: Enjoy warm. For a little shine, brush the edges with a touch of melted butter and sprinkle with chopped parsley.