For the roasted garlic: Preheat the oven to 400 degrees F.
In a small ramekin or pouch formed out of aluminum foil, add the garlic and enough olive oil to cover. Season with salt and pepper, then cover or close with aluminum foil. Roast until the garlic is tender but not browned, about 25 minutes.
For the dip: In a food processor, add the peas, peppers and onions, parsley, cream cheese, lemon juice, a pinch of salt and a few grinds of pepper. Add the roasted garlic (reserve some the olive oil for the garnish) and pulse until smooth. Taste and season with more salt if needed.
For the garnish: Serve the dip in a bowl with a drizzle of the olive oil from the roasted garlic and a sprinkle of the parsley and walnuts. Serve with pita chips, raw vegetables and grissini for dipping.