The juices from the simmering fruit, make the cake so moist.
I usually make blueberry coffeecake, but i love blackberries, so I figured I'd try to make a coffeecake w/ blackberries. It took a few tries, but here it is...
Heat oven to 350. Spray a bundt pan w/ cooking spray. In saucepan, combine fruit and 1/4 cup water. Bring to boil, reduce heat. Cover and simmer until tender, about 5 mins.
Combine in small bowl, 1/4 cup sugar and cornstarch. Stir into fruit mix in saucepan. Cook, stirring until bubbly. Cook 2 min more. Set aside. In bowl, mix together 1/2 cup sugar, 1-1/2 cups flour, baking powder and baking soda. Cut in 4 tbsp butter until crumbly.
In another bowl, combine egg, buttermilk and vanilla. Add to flour mix until just moistened. Spread 1/2 the batter into pan. Spread fruit mix over batter. Drop remaining batter in mounds over fruit filling. In small bowl, combine remaining 1/4 cup sugar and 1/4 cup flour. Cut in remaining butter until crumbly. Sprinkle over batter. Bake about 35-40 min, or until toothpick inserted in center comes out clean.