Step 1: Prepare pineapple and jalapeños. Core and slice the pineapple into desired pieces. Wash jalapeños thoroughly. Wearing gloves, slice jalapeños into 1/8-inch rounds. For less heat, remove seeds and membranes.
Step 2: Combine syrup ingredients. In a large non-reactive pot (stainless steel or enameled cast iron), combine sugar, apple cider vinegar, garlic powder, onion powder, turmeric, and cayenne pepper (if using). Bring to a boil over medium-high heat, stirring until sugar is fully dissolved.
Step 3: Add pineapple and jalapeños. Add the sliced pineapple and jalapeños to the boiling syrup. Reduce heat to a gentle simmer.
Step 4: Simmer and candy. Continue to simmer gently for at least 1 hour to 1 hour 15 minutes, stirring occasionally. The pineapple and jalapeños will soften, and the syrup will thicken and become more translucent.
Step 5: Jar the candy. Carefully ladle the hot pineapple cowboy candy and syrup into clean, sterilized pint jars, leaving 1/2-inch headspace. Ensure pineapple and jalapeños are submerged in syrup.
Step 6: Cool and store. Wipe jar rims clean, apply lids and bands. Let jars cool completely on the counter. Once cool, refrigerate for up to 2-3 weeks. For longer storage, process jars in a boiling water bath canner for 10 minutes, following proper canning guidelines.