Preheat oven to 450°F. Place the pineapple in an oven-safe pan or baking sheet and roast for 15 to 20 minutes or until slightly charred. Set aside to cool.
In a glass container with lid, combine a third of the pineapple with the mezcal. Let the mixture sit at room temperature for at least 48 hours. Strain with a cheesecloth – reserving the infused mezcal. Refrigerate the remaining roasted pineapple.
Onced mezcal is ready, combine all but 2 chunks of roasted pineapple, lime juice, mezcal, tequila, agave nectar and bitters in a blender and puree.
Working in two batches, pour mixture into an ice-filled cocktail shaker and shake well.
Prep your cocktail glasses by wetting the rims with a lime wedge. Mix 1:1 salt and chile powder in a small plate. Roll or dip glass in salt mixture to coat the rim. Fill with ice.
Strain cocktail into the glass and garnish with roasted pineapple and a lime wedge.