01 - Preheat oven to 375°F (190°C). Lightly grease a standard 12-cup muffin tin or line with paper liners.
02 - In a large skillet, melt the butter over medium heat. Add the onion and minced garlic; sauté until fragrant and translucent, about 2 to 3 minutes.
03 - Stir in flour and cook for 1 minute. Gradually whisk in the milk and chicken broth, stirring constantly until the mixture thickens, about 2 to 3 minutes.
04 - Add diced chicken, mixed vegetables, thyme, salt, and pepper to the skillet. Stir thoroughly and simmer for 2 to 3 minutes. Remove from heat and allow to cool slightly.
05 - Separate biscuit dough into 12 equal portions. Flatten each and press into the bottom and up the sides of each muffin cup to form a shell.
06 - Spoon approximately 2 tablespoons of chicken mixture into each muffin shell.
07 - Evenly sprinkle shredded cheddar cheese over each filled muffin. Top each with grated Parmesan cheese.
08 - Place muffin tin in oven and bake for 20 to 25 minutes, or until biscuits are golden and cheese is melted and bubbling.
09 - Allow muffins to cool for 5 minutes before removing from tin. Garnish with fresh parsley if desired.