In a high-powered blender or food processor combine the garlic, chili powder, paprika, chipotle chilies, pineapple juice, vinegar and 1 cup of the pineapple chunks. Blend until completely smooth. Set the pineapple sauce aside.
Heat a large skillet over medium-high heat and add the olive oil. Add the cauliflower and onions, season with salt + pepper. Cook for 12-15 minutes or until the cauliflower is tender and the onions have caramelized.
Reduce the heat to low stir in the pineapple sauce, the remaining cup of pineapple chunks and the jalapeno. Simmer for 8-10 minutes or until the sauce has reduced and coats the cauliflower, there will still be sauce left in the pan, this is good. Remove from the heat and stir in the cilantro.