I have been craving some rhubarb crumb bars, last year at this time we were house-sitting in a wonderful home that had an amazing garden and all the rhubarb we could eat. It was the first time I had used it, I think even eaten it before, and I fell in love. I only had frozen blackberries on hand this time and decided to use those. I love these crumb bars, the texture of the cake on the bottom with the fruit in the middle, divine. Although it seems to always happen that the middle is always doughy for me. I take it out anyways, because I'm afraid of the edges becoming overdone. The edges are perfect, but the middle was so not perfect. I think my oven is a little hot, I should probably bake things at a lower temperature for longer, I guess I'll have to get an oven thermometer and try this again. But rhubarb is a lot better.