Ingredients
Streusel:
1/4 cup sugar
3 packed tablespoons dark brown sugar
1/2 cup walnuts, toasted and coarsely chopped
2 teaspoon vanilla extract
1/2 teaspoon ground cinnamon
Cake:
2 cups unbleached all-purpose flour
1 teaspoon baking soda
1/2 teaspoon fine salt
Generous pinch freshly grated nutmeg
Generous pinch ground mace
3/4 cup unsalted butter, plus more for the pan, room temperature
1 cup sugar
2 large eggs, room temperature
1 cup sour cream
1 1/2 teaspoons vanilla extract
Directions
Make the streusel by mixing the sugar, brown sugar, walnuts,
vanilla, and cinnamon together in a small bowl. Set it
aside.
Preheat the oven to 350 degrees F. Generously brush a 9-
x 2-inch cake pan with butter. In a medium bowl whisk the
flour, baking soda, salt, nutmeg and mace together and set
it aside.
In a standing mixer fitted with the paddle attachment,
or with an electric hand-held mixer, cream the butter and
sugar on medium speed until light and fluffy. Add the eggs,
one at a time, mixing until incorporated. Mix the vanilla
with the sour cream. Add the flour mixture in 3 parts to the
butter mixture, alternating with the sour cream in 2 parts
until just combined.
Spread half the batter into the prepared pan and
sprinkle with half the streusel. Spoon the remaining batter
on top and spread it out with a spatula. Scatter the
remaining streusel over the top of the batter. Bake the
coffee cake for 1 hour and about 10 minutes, or until golden
brown and a tooth pick inserted into the center of the cake
comes out clean. Cool on a rack for 10 to 15 minutes before
serving.