To make the vinegarette: place 1/2 the pint of blueberries in the blender with the balsamic vinegar, olive oil, lemon juice, and garlic.Blend on high until pureed and add salt and pepper to taste. Set aside.
Toss together remaining blueberries, shallot, pistachios, blue cheese, and spinach. Toss in with desired amount of dressing and serve.