Put the sliced strawberries, honey and vanilla in a blender and add enough water to blend to a smooth consistency (about 3 tablespoons). Pour the strawberry sauce into a small pitcher or bowl and set aside.
Add the frozen yogurt and milk to the blender and blend until smooth. Pour some strawberry sauce into two tall glasses. Add the milkshake mixture and top with the whole strawberries, marshmallows and more strawberry sauce. Serve immediately.