In a large bowl toss the lettuce, blue cheese, pears, walnuts and cranberries if using them. Set aside.
To make the dressing, mix the maple syrup, vinegar, mustard, salt and pepper in a small bowl with a fork until combined. While continuing to stir, slowly pour in the olive oil until mixed. If it doesn't totally emulsify that's okay.
Pour over the dressing just before serving.
To make ahead: Mix the salad ingredients and dressing and store separately in the refrigerator until ready to serve.
To make this recipe for a larger crowd, estimate about 1 cup of lettuces per person.