Cinnamon Streusel Coffee Cake

This is almost a repost of something I did over at Slashfood this week, but the cake is very good and I wanted to share it here, too. This Cinnamon Struesel Coffee Cake is a Martha Stewart Living recipe that I adapted by changing the spicing slightly. It was originally meant to be a cardamom streusel cake, but I was not going to toast and grind a bunch of whole cardamom pods just to make streusel when cinnamon is such a natural fit for coffee cake. I did use some cardamom , but it was pre-ground.
If you're not familiar with coffee cake, it gets its name because it is designed to be served with coffee or tea, as part of a mid-morning or mid-afternoon meal, not for dessert. The reason must be that coffee cakes are never frosted and, as you know, almost anything is acceptable breakfast food when it doesn't have a thick layer of frosting. This cake is very rich, moreso than some desserts and definately less good-for-you than something I might make on a whim in the afternoon but it is classic comfort food and a great choice for special occasions or a brunch when you're having guests.
The cake very nearly has more streusel than batter, and it was difficult to spread the batter over the streusel layer without swirling it into the cake. I used my spatula to gently and carefully push the batter over to the sides of the pan. I used half non-fat yogurt and half buttermilk instead of all low-fat yogurt. The original recipe gave an incorrect baking time, which I have corrected here. It only called for 50 minutes in the oven, when the cake needed at least 10 more minutes.
The cake is moist, rich and delicious. It is not a light cake, but it is very tender and does not seem heavy or dense. I loved how simply pressing the streusel mixture into big chunks before spreading it on the cake resulted in professional looking and tasting topping. Aside from the hitch with the incorrect baking time being given in the recipe, I didn’t have any problems and found the recipe to be fairly simple. My hands got messy making the streusel, but I just had to avoid answering the phone while I did it.
The recipe originally said this serves 10-12, but I far prefer to cut it into 16 or 20 smaller slices. You can always take a second piece.

Cinnamon Streusel Coffee Cake
For the Streusel:
2 ¾ cups ap flour
2 tsp cinnamon
1 tsp cardamom (or additional cinnamon)
1 cup brown sugar
½ tsp salt
1 cup unsalted butter, softened

For the Cake:
2 ½ cups ap flour
1 tsp baking powder
½ tsp baking soda
2 tsp cinnamon
½ tsp salt
¾ cup unsalted butter, very soft
1 ¼ cups sugar
3 eggs
1 tsp vanilla extract
1 ¼ cups plain yogurt or buttermilk (low fat or nonfat)

Preheat the oven to 350F. Grease a 10-inch tube pan.
Make the streusel:
Place all your streusel ingredients, except for the butter, in a large bowl and stir together. Cut the butter into 10 or 12 large chunks and add them to the bowl. Using your hands, rub the butter into the flour mixture until the mixture is crumbly. Some pieces can be large - the size of an almond or pecan - but they shouldn't all be that big. It may take 4-5 minutes because it is a bit harder to work with soft butter than firm. Set aside.
Make batter:

Combine flour, baking powder, baking soda, cinnamon and salt in a medium bowl and whisk until well combined.
In a large bowl, cream the butter and sugar together on medium-high speed until smooth and fluffy, about 3 minutes. Beat eggs in one by one, followed by vanilla extract.
Alternately add the yogurt (or buttermilk) and the flour mixture, making sure to end with an addition of dry ingredients. Don't forget to scrape down the sides of the bowl with a spatula as you mix.
Scrape half of your batter into the greased, 10-inch tube pan that you prepared earlier. Smooth batter with a spatula and top with 2 ½ cups of streusel. Scrape remaining batter into pan, on top of streusel, gently spreading it to the sides of the pan with your spatula. Use your fingers to squeeze remaining streusel together into large and small chunks, then top batter with all remaining streusel.
Bake at 350F for 60-70 minutes, until a tester comes out clean (mine took about 64 minutes).
Place cake on a wire rack and allow to cool for 15 minutes. Run a sharp knife around the around the outer and inner edges of the pan. Remove tube portion with cake attached. Run knife over the bottom, loosening the cake. Gently replace cake in the pan, which will support it as you turn it upside down. Place a clean dishtowel on top of the pan and a baking sheet on top of that. Carefully flip pan over, turning cake out onto the baking sheet. Reinvert onto wire rack. Allow to cool completely.
Serves up to 20.