Cook the pasta until al dente, as per package instructions.
Soak cashews in water for at least 30 minutes, then ground into a fine, very smooth paste.
Heat a heavy skillet and place the whole tomatoes on it. If the skillet is large enough, place the jalapenos and the garlic cloves, with skins on, in the skillet too. If not, roast these one at a time.
Roast the tomatoes until the skin starts to char and brown spots appear. Turn them around and let them cook on all sides until the skin is fairly brown. Do the same for the jalapenos and the garlic.
Remove everything to a plate. Roast the tomatoes further in an oven to intensify the sweetness (optional). Cut the tomatoes in half and put them in an oven-safe dish, cut side up, and place in a 500-degree preheated oven for 20 minutes.
Once the tomatoes cool, place them in a blender along with the jalapeno peppers (deseeded for less spice) and chipotle chilli. Peel the garlic and add it to the blender too.
Blend the tomatoes into a puree. No need to add water.
Heat olive oil in a skillet. Add the tomato-chipotle mixture to the skillet and cook until it is reduced to the consistency of tomato paste and has become darker, for about 8-10 minutes.
Add the cashew cream and mix well.
Add salt to taste. Add some ground black pepper for more flavour (optional).
Add the cooked pasta, basil, and strips of roasted bell peppers (instructions below) and toss.
For roasted bell peppers:
Place the bell peppers in an oven-safe dish with deep sides (don't use a flat plate because some juices might run from the peppers).
Preheat an oven to 500 degrees. Place the peppers in the oven and let them roast, turning them occasionally, until the skin is evenly brown and charred.
Cool the peppers and then peel off the skin and remove seeds.