Preheat oven to 450°F. Wrap beets tightly in individual pieces of aluminum foil and place in a pie dish or on a rimmed baking sheet. Roast until tender (you should be able to pierce them easily with a knife), about 1 hour. Unwrap and set aside to cool. When cool enough to handle, rub with a paper towel to remove skins, or peel with a paring knife. Cut into quarters.
Bring a medium saucepan of water to a boil. Cook fregola in boiling water for 12 minutes or according to package directions; drain. Transfer to a large bowl and stir in oil, salt and pepper until well combined.
Make pesto: Using a sharp chef's knife, mince garlic with salt, then slide flat side of knife over mixture a few times to create a paste. Place parsley, nuts and cheese in work bowl of a food processor or a heavy-duty blender (such as a Vitamix). Add garlic paste and pulse to combine. With processor running on low, slowly pour in oil until blended.
Stir pesto into fregola. Divide fregola among 4 bowls, then top each with 4 beet quarters. Grind some pepper on top, if desired, and serve.
Adapted with permission from Eating in Color, by Frances Largeman-Roth. Stewart, Tabori & Chang; January 2014.