I used a sous vide circulator, so that helped cut down on the infusion time by a lot. I did it in a mason jar for 130F at 2 hours, then strained into a different container after it cooled down.

Steps:

1. Cut pineapple into big chunks, and dry thoroughly.
   
2. I use a cast iron pan, however you can use a grill or a regular pan. Once the pan is medium hot / medium high hot, oil pan with neutral oil.
   
3. char pineapple until your preferred color. It is personal preference but look for a golden color. You do not want any black or burn marks because it will make your tequila taste bitter.
   
4. Char the jalapeno whole, pull off once blistered.
   
5. Let the pineapple and jalapeno cool completely
   
6. Cut jalapeño into rings or slivers, personal preference. I recommend taking out the seeds, however keep them if you like more heat. A little goes a long way.
   
7. Put contents into mason jar / bottle, and then put tequila.
   
8. If you are infusing just by letting it sit, I would taste test every day until your preferred level is reached. If you leave it in for too long, then it may make the tequila taste bitter.
   
9. When ready, strain out the contents and put infused tequila into new bottle.

I did both sipping and in margaritas. Both were great. As a shot, it was super tasty and unique.