1In a blender ,combine strawberries and preserves.In a small bowl,make a paste by mixing cornstarch and vanilla.Add to strawberries mixture.Set aside.
2In a large bowl mix together,sugar,flour,baking powder and soda.Add butter cubes,and using your fingertips, rub them in until mixture resembles large coarse crumbs.Put 1/2 cup aside,for topping.
3Add sour cream,egg,and vanilla to crumbs in a large bowl.Mix well.Dough is very sticky.Drop dollops of half the batter into 9 inch prepared springform pan.Pat batter across bottom of pan and about 1 inch sides up.Spread strawberry puree leaving 1/2 inch border .
4Cover with remaining batter.Add 2 teaspoons of brown sugar to 1/2 cup crumbs.Mix well and sprinkle evenly over the cake.
5Bake 45 minutes in 375 degrees preheat oven.Serve with vanilla or strawberry ice cream.