Step 1Pour the water into a large pitcher (at least 3-quart capacity) or blender and add the piloncillo. Stir or blend until the sugar dissolves.
Step 2Meanwhile, heat the canela sticks in a small skillet over medium-high heat until they smell fragrant and nutty and start to unfurl, about 3 minutes. Place the hot canela sticks in the pitcher along with the pineapple peels and cores and give everything a stir.
Step 3Drape a piece of cheesecloth over the top of the pitcher and secure it with a rubber band or kitchen twine. Set the pitcher out on your counter in an area that gets no sunshine or place it in a cupboard with plenty of ventilation. Let the brew sit for 2 days.
Step 4When ready to serve, use a spoon to skim off and discard any white scum floating on top of the liquid (there might not be any). Pour the brew through a fine strainer into another clean, large pitcher. Pour as much as you want to drink in a small saucepan and heat it over medium heat until hot. Pour the tepache into mugs and serve warm. Refrigerate any leftover tepache for up to 5 days.
Step 5For spiked tepache: Stir in 2 ounces mezcal or tequila to your mug of warm tepache.