Vanilla Crumb Cake

Makes one 10-inch round coffee cake

Crumb Top
1 1/2 cups cake flour
2/3 cup sugar
1 1/2 teaspoon ground cinnamon
1 teaspoon vanilla extract
10 tablespoons cold unsalted butter - cut into small pieces (1 stick plus 2 tablespoons)


Cake Batter
6 tablespoons unsalted butter - softened (3/4 stick so basically the rest of what was left after the crumb topping)
3/4 cup sugar
3 large eggs
2 teaspoons vanilla extract
2 1/4 cake flour - unsifted
1 1/2 teaspoons ground cinnamon
1 teaspoon baking powder
1 teaspoon baking soda
1/4 teaspoon salt
1 cup sour cream (not fat reduced)

Preheat the oven to 350 degrees (325 degrees for a dark-finish pan). Line a 10-inch springform pan with parchment, grease the bottom and sides and set aside.

To make the crumb top, in the bowl of a heavy-duty electric mixer fitted with the paddle attachment, combine the flour, sugar; and cinnamon. Cut in the vanilla and cold butter on low speed until coarse dry crumbs are formed. Pour into a small bowl and set aside. If not using immediately, refrigerate until needed.

To make the cake batter, without cleaning the mixing bowl, cream the butter and sugar on medium speed until light and fluffy, about 1 minute. Add the eggs, one at a time, and the vanilla extract and beat well on medium speed for 30 seconds. The mixture will be loose. Add the flour; cinnamon, baking powder; baking soda, and salt and beat on low speed for 15 seconds. Add the sour cream and beat on medium-high speed only until the lumps smooth out and the mixture looks fluffy, about 30 seconds on medium-high speed. Do not overbeat.

Spread the batter evenly into the prepared springform pan. Sprinkle the top evenly with the crumb topping. Bake on the center rack of the oven for 45 to 55 minutes, or until the top is crisp and feels firm when gently touched in the center; the cake separates slightly from the sides of the pan, and a cake tester inserted into the center comes out clean (it may be a bit moist; that's okay). Do not overbake, or the cake will be dry.

Remove from the oven and cool in the pan on a wire rack for 5 minutes before removing the sides of the pan. Let cool at least 30 minutes before serving warm, or cover in plastic wrap to serve later at room temperature.

Store at room temperature for up to 3 days.

NOTES:
I made this in a 9x9 square glass cake pan and it worked fine. I have done it in the springform pan and presentation is nice - by cutting into wedges, but works fine in a 9x9 square cake pan too.