Preheat oven to 350 degrees.
In a blender or small food processor puree 1/4 cup parsley with 1/4 cup oil. Pour mixture through a fine sieve set over a bowl, pressing hard on solids, and discard solids.
In a small baking pan toast pine nuts and cumin seeds, stirring occasionally, until nuts are golden, about 10 minutes.
In a colander rinse and drain chickpeas and in a food processor puree 1/2 cup with garlic until garlic is finely minced. Add tahini, water, lemon juice, salt, remaining chickpeas, and remaining 1/2 cup olive oil and puree until smooth. Recipe may be prepared up to this point 3 days ahead. Keep hummus and parsley oil chilled, covered, and pine nuts and cumin seeds in an airtight container at room temperature. Bring parsley oil to room temperature before using.
Strip leaves from additional parsley sprigs. Divide hummus between 2 shallow dishes and smooth tops. Drizzle hummus with parsley oil and sprinkle with parsley, pine nuts, and cumin seeds.
Serve hummus with toasted pita chips.
*available at natural foods stores and some supermarkets