In medium bowl, combine grapes, yogurt and vanilla. Line 9-inch square metal baking pan with parchment paper then, using 1-ounce scoop, place mounds of grape-yogurt mixture on sheet. Freeze until set, about 3 hours, or overnight.
Place chopped chocolate in small, wide microwaveable bowl. Microwave 1 minute on medium power. Stir and repeat. Stir then microwave 30 seconds, repeating as needed until melted and smooth.
Stir in oil. Dip bottoms of frozen clusters in chocolate to coat and return to pan.
Store frozen clusters in airtight container in freezer up to 1 week.
Notes
Nutritional information per serving: 100 calories; 3 g protein; 12 g carbohydrates; 4.5 g fat (41% calories from fat); 2.5 g saturated fat (23% calories from saturated fat); 0 mg cholesterol; 10 mg sodium; 2 g fiber.