Sour Cream Coffee Cake

The origin of this, I believe, is the Joy of Cooking.

Preheat oven to 180C.

Prepare streusel and set aside:

• 100g plain flour
• 165g soft light brown sugar
• 100g chopped walnuts or pecans
• 1 teaspoon ground cinnamon
• 1/4 teaspoon salt
• 90g butter, melted

Whisk together thoroughly and set aside:

• 300g plain flour
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• 1/2 teaspoon salt

Combine in another bowl and set aside:

• 300ml sour cream (300 ml)
• 1 teaspoon vanilla extract

In a large bowl, beat on high speed until lightened in colour and texture, 3-4 minutes:

• 60g softened (but not oily) butter
• 200g caster sugar

Beat in one at a time:

• 2 large eggs

Add the flour mixture in 3 parts, alternating with the sour cream mixture in 2 parts (therefore it goes 1/3 flour, 1/2 sour cream, 1/3 flour, 1/2 sour cream, 1/3 flour), beating on low speed and scraping the sides as necessary. Spread into a greased and lined 33 x 23cm (13"x9") pan; the cake is quite delicate, so the lining can be used like a sling to lift it out. I squeeze the streusel to form small clumps, then sprinkle over the batter, starting with the edges. Bake until a toothpick inserted in the centre comes out clean, about 25 minutes. Serve warm! Although it gets better when left for a day.