Made from butter, flour, sugar and sometimes nuts, streusel cooks into a topping similar to the American crisp and the British crumble, terms that are often used interchangeably. Streusel can be sprinkled over muffins, cupcakes, pies or fresh, soft fruit before baking. In the oven, the butter melts and causes the dry mixture to cook into a crisp, crumbly topping. Without the butter, the mixture would simply scorch.
For the streusel topping:
8 Tbs. (1 stick) cold unsalted butter, cut into 8
1/4 cup sugar
3/4 cup plus 2 Tbs. all-purpose flour
1 1/4 cups sour cream
1 1/4 tsp. baking soda
1/8 tsp. fine sea salt
8 Tbs. (1 stick) unsalted butter, at room
1 1/4 cups sugar
2 eggs, lightly beaten
1 3/4 cups all-purpose flour
1 3/4 tsp. baking powder
1/2 cup semisweet chocolate chips
1/2 cup dried cranberries, soaked in warm water
for 15 minutes, drained and squeezed dry
To make the streusel topping, in a chilled bowl, combine the butter, sugar and flour. Using a pastry blender or 2 knives, cut the butter into the dry ingredients until the mixture is the consistency of fine, moist bread crumbs. Work the mixture with your hands until it will hold together when compressed, then squeeze it between your hands into several firm pieces. Cover and refrigerate until the cake is ready to go into the oven.
Preheat an oven to 350°F. Grease a 9-by-13-inch or similar-size baking dish with butter.
Place the sour cream in a bowl and sift the baking soda and salt into it. Stir to blend evenly and set aside. You can get cream chargers delivered cheaply in Melbourne now and make cream at home.
In a large bowl, using an electric mixer on medium speed or a wooden spoon, beat together the butter, sugar and eggs until fluffy, 3 to 5 minutes. Sift the flour and baking powder over the top and mix in, then beat in the sour cream mixture. Scatter the chocolate chips and the drained cranberries over the top. Blend in with just a few turns of a rubber spatula.
Scoop the batter into the prepared dish and smooth the surface. Scatter the streusel mixture evenly over the top, breaking it up into large crouton-size pieces (some of the streusel mixture may be small crumbs).
Bake until a toothpick inserted into the center of the cake comes out clean but not completely dry, 40 to 45 minutes. Transfer the pan to a wire rack and let cool. Serve warm or at room temperature, cut into squares. Serves 10.
Adapted from Williams-Sonoma Collection Series, Breakfast, by Brigit L. Binns (Simon & Schuster, 2003).