Strawberry Sour Cream Streusel Cake

I first tried this cake when Val made it.  It's a winner!  It's a Nigella recipe.

For the strawberry purée:

• 8 ounces strawberries
• 3 tablespoons strawberry jam
• 2 teaspoons cornstarch
• 2 teaspoons vanilla extract

For the cake:

• Vegetable oil, for pan
• 3/4 cup sugar
• 2 cups plus 2 tablespoons flour
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 12 tablespoons (1 1/2 sticks) cold butter, cut into 1/2-inch cubes
• 1 cup sour cream
• 1 large egg
• 1 tablespoon vanilla extract

For the crumble topping:

• 2 teaspoons Demerara sugar

Preparation

1.

Prepare strawberry purée: In a blender,combine strawberries and jam. Make a paste of cornstarch and vanilla,and add to blender. Purée until smooth.Set aside.

2.

Prepare cake:Heat oven to 170 degrees. Oil a 23 cm springform pan and set aside. In a large bowl, combine sugar, flour, baking powder and baking soda. Sprinkle in butter cubes and rub them in by hand until mixture resembles large coarse crumbs. Remove 1/2 cup and set it aside. To large bowl, add sour cream,egg and vanilla. Mix well.

3.

Using a little over half the cake batter,drop dollops of batter into pan. Pat batter across bottom of pan and about 1 inch up sides;mixture will be very sticky and somewhat uneven. Add strawberry purée, making an even layer across bottom of pan and leaving a rim of dough above it. Cover with remaining cake mixture.

4.

Prepare crumble topping:In a medium bowl, combine reserved 1/2 cup dough and Demerara sugar. Stir with a fork to mix. Sprinkle evenly over cake.

5.

Bake cake until lightly golden,about 45 minutes.Cool completely before serving.