Nigella Lawson'S Very Smart Strawberry Streusel Cake

• For the jam layer:
• 8 ounces fresh strawberries, hulled
• 3 tablespoons strawberry jam (I've also used raspberry, and I bet other types-apricot!-would be good too)
• 2 teaspoons cornstarch
• 2 teaspoons vanilla extract
• For the cake and crumb topping:
• 3/4 cup sugar
• 1 cup all-purpose flour
• 1 cup plus 2 tablespoons whole wheat pastry flour (or substitute all-purpose flour)
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 12 tablespoons (1 1/2 sticks) cold salted butter, cut into 1/2-inch cubes
• 1 cup sour cream
• 1 large egg
• 1 tablespoon vanilla extract
• 2 teaspoons Demerara or turbinado sugar

1. In a blender, combine the strawberries and jam and process until combined. Make a slurry of the cornstarch and vanilla extract, add to blender, and blend until smooth. Set aside for later.
2. Preheat the oven to 375u0b0 F and grease a 9-inch springform pan.
3. In a large bowl, whisk together the sugar, flours, baking powder, and baking soda. Sprinkle in butter cubes and use your fingers to rub them in-as if you were making pie dough-until mixture resembles large coarse crumbs with pea- and walnut-sized butter pieces.
4. Remove 1/2 cup and set it aside for the topping in a medium bowl.
5. To the large bowl, add sour cream, egg, and vanilla. Mix well.
6. Dollop a little over half of this batter into pan. With slightly damp hands, pat the batter across bottom of pan and about 1 inch up sides; the mixture will be very sticky and somewhat uneven.
7. Pour over the strawberry puree in an even layer over the batter, leaving a rim of dough around it. Cover with blobs of remaining cake mixture, trying to spread them as evenly as possible and using damp hands to thin them out. Don't stress about it! (Trust me.)
8. Add the Demerara sugar to the reserved 1/2 cup dough and stir with a fork to mix. Sprinkle evenly over cake.
9. Bake cake until lightly golden, about 45 minutes. Cool completely before serving.

layer, fresh strawberries, strawberry, cornstarch, vanilla, cake, sugar, flour, whole wheat pastry flour, baking powder, baking soda, butter, sour cream, egg, vanilla, turbinado sugar

Taken from food52.com/recipes/54840-nigella-lawson-s-very-smart-strawberry-streusel-cake (may not work)