Make the green harissa. Char the peppers over a gas burner or under a broiler until the skin is blackened all over. Remove from the heat and place in a bowl and cover with a towel or plastic wrap for 10 minutes. Slice off the stem and place the peppers, garlic, lemon juice, cumin, coriander, salt, honey, cilantro, pepitas and a few grinds of black pepper into a food processor and pulse until combined. Drizzle in the olive oil and process until smooth.
Make the grilled cheese. Slather the green harissa on the insides of each slice of bread. Assemble with spinach leaves and cheese. Pre-heat a cast iron skillet or grill pan over medium heat. Brush the outsides of the sandwich with olive oil and grill on each side until the cheese is melted.