Pour the 4 cups apple cider into a 2- to 3-quart saucepan. Add the cinnamon sticks, lightly crushed cardamom pods, cloves, ginger slices, and lightly crushed black peppercorns.
Place the saucepan over medium heat and bring the cider to a gentle simmer. Avoid letting it reach a vigorous boil.
Reduce the heat to low and simmer uncovered for 10 minutes, until the cider is hot and fragrant.
Remove the saucepan from the heat. Add the 4 black tea bags, making sure they are submerged in the hot cider.
Steep the tea for 4 minutes. Remove and discard the tea bags without squeezing them.
Stir in the 1 tablespoon maple syrup.
Strain the chaider through a fine-mesh strainer into a heatproof pitcher or directly into mugs. Discard the spices and ginger.
If making creamy chaider, warm the 1 cup whole milk separately in a small saucepan over medium-low heat for 3 to 4 minutes, until steaming but not boiling.
Divide the warmed milk evenly among four mugs, then add the hot strained chaider. For a stronger apple-forward drink, simply serve the chaider without milk.
Serve immediately while hot and aromatic.