Begin by roasting the red bell peppers. Place them on a baking sheet under the broiler and roast, turning occasionally, until the skin is charred on all sides. This should take about 10 minutes.
Transfer the roasted peppers to a bowl and cover with plastic wrap, allowing them to steam for 10 minutes. Once cooled, peel off the skin, remove the seeds and stems, and place the flesh in the bowl of a food processor.
Add the toasted walnuts, garlic, bread crumbs, olive oil, pomegranate molasses, ground cumin, smoked paprika, cayenne pepper, salt, and lemon juice to the food processor with the red peppers.
Pulse the mixture until smooth, scraping down the sides as necessary to ensure even blending. If the dip is too thick, you can add a tablespoon of water to reach the desired consistency.
Taste and adjust the seasoning if necessary. For a richer flavor, you can add more pomegranate molasses or a pinch more salt.
Transfer the Muhammara to a serving bowl. It can be served immediately or refrigerated for an hour to allow the flavors to meld.
Garnish with a drizzle of olive oil and a sprinkle of chopped walnuts before serving.