Preheat your oven to 375°F (190°C).
Roll out the pie crust and, using a cookie cutter, create mini crust circles. Fit these into a muffin tin, pressing gently to shape them.
In a medium-sized mixing bowl, whisk together the eggs, milk, salt, and black pepper until smooth.
Mix in the diced turkey, ensuring the turkey is well incorporated within the egg mixture.
Stir in the shredded cheddar cheese to the mixture, combining them well.
Add in the finely chopped spinach, bell peppers, and onions. Mix everything until all ingredients are well-distributed.
Carefully pour or spoon the egg mixture into each mini crust, filling them about 3/4 of the way full.
Place the muffin tin in the oven and bake the Mini Turkey Cheddar Quiches for 20-25 minutes or until the centers are set and the edges are golden brown.
Once done, remove from the oven and let them cool for 5 minutes before serving.