Roast peppers under the broiler until they are slightly charred on all sides. Let cool slightly and peel skin off with a paper towel. Cut up peppers and discard seeds.
While peppers are roasting, saute onion and garlic in olive oil until softened and fragrant, about 3-5 minutes on medium heat.
Add red curry paste to the onion and garlic mixture and continue to saute for a couple more minutes until the paste has dispersed in the pan and has covered the onions and garlic.
Add peppers, onion and garlic mixture, pineapple, coconut milk and fish sauce to a blender or food processor. Blend until smooth.
Return to the stovetop and add in lime juice. Stir in 1/4 cup of heavy cream and let thicken. Season with kosher salt and pepper to taste. Serve with fresh basil and drizzled crema.