Pour oil over cut side of garlic bulb and rub into skin. Double wrap garlic in foil and roast 20-25 minutes.
Combine walnuts, feta, milk, oregano, parsley, black pepper, red pepper, and garlic clove in food processor. Pulse until spread is smooth. Scrape spread into serving dish with spatula. Drizzle dip with extra virgin olive oil and serve with roasted garlic and pita bread.