A very easy to make blueberry coffee cake. I always double the topping so I included the measurements for the doubled amount. This makes a great dish to bring for a potluck. It will disappear very quickly. You can add nuts if you wish in the topping. I got this from a friend who always used it as a quick item to make for a party. She could make it up, stick it in the oven, finish getting ready and when guests arrived, served it very warm with butter.