Cut tops and bottoms from 4 medium to large red bell peppers. Remove the core and seeds from the peppers and slice the main part of the pepper to form one long strip. Remove the stem from the tops of the peppers. Arrange all the pieces on a baking sheet covered with foil.
Move oven rack to highest level and roast peppers under the broiler until skin becomes black and bubbled in spots (7-10 minutes).
Remove peppers from oven and transfer to a bowl. Cover with foil and allow to steam for at least 10 minutes. Peel skin from cooled roasted pepper pieces (don't worry if there are small pieces of skin that you can't remove - your muhammara will be great as long as you remove the majority of the skin)
Combine the peeled bell pepper pieces, 1 cup walnuts, 1/4 cup bread or cracker crumbs, 3 Tablespoons pomegranate molasses, 2 Tablespoons olive oil, 3/4 teaspoon salt, 1/2 teaspoon ground cumin, and 1/4 teaspoon cayenne in a food processor, blender or large bowl. Pulse in the food processor or blender (or use an immersion blender) to puree the ingredients together. Refrigerate for at least 30 minutes, until chilled. Serve with fresh pita, pita chips, crackers and/or raw vegetables.
Notes
If you don't have pomegranate molasses, use 3 Tbsp lemon juice, 1 Tbsp molasses and 1 tsp honey instead.