1/2 cup baby spinach leaves, firmly packed
1/2 cup frozen blueberries
1/2 cup plain low-fat yogurt
1/2 cup unsweetened white grape juice
1 Tbsp agave nectar
Zest of half a lemon (or half a Meyer lemon, or half a tangerine)
5 ice cubes
Place all ingredients except the ice in a blender. Process until almost smooth. Add the ice cubes and process until completely smooth.