This recipe is adapted from Carole Walter's recipe for Chocolate Ripple Coffee Cake in Fine Cooking, October 29, 2008. You're going to love it! It's one of my favorite go-to recipes! I'll bet you have most of the ingredients in your pantry and fridge. This coffee cake also freezes well.
CHOCOLATE MARBLE COFFEE CAKE
For the cake:
3 cups sifted cake flour
1-1/2 tsp baking powder
1 tsp baking soda
3/4 tsp salt
1-1/4 cups unsalted butter, slightly softened
1-1/2 cups superfine sugar
4 large eggs
2 tsp vanilla extract
2 cups sour cream
For the filling:
1/2 cup toasted pecans
6 oz coarsely chopped dark chocolate (64-75% cacao)
3 Tbsp granulated sugar
3 Tbsp light brown sugar
3 Tbsp Dutch-processed or natural cocoa powder (Tip: Natural vs Dutch-processed)
For the streusel topping:
4 Tbsp unsalted butter
2/3 cup all-purpose flour
1/4 cup toasted pecans, coarsely chopped
2 Tbsp granulated sugar
2 Tbsp light brown sugar
1/2 tsp ground cinnamon
1/4 tsp baking powder
1/4 tsp table salt
Position rack in center of oven -- 350ºF.
Butter and flour 10-inch tube pan with removable bottom.
Make topping: In 2-quart saucepan, heat butter over medium heat until almost melted. Remove from heat and cool to tepid. In medium bowl, combine flour, pecans, both sugars, cinnamon, baking powder, and salt, and stir with fork. Add flour mixture to butter and stir until evenly moistened and crumbly.
Make filling: In food processor, pulse pecans, chopped chocolate, both sugars, and cocoa until chocolate is finely chopped, 12 to 14 pulses. Set aside 1/2 cup of mixture as additional topping.
Make cake: In medium bowl, whisk flour, baking powder, baking soda, and salt. In bowl of stand mixer fitted with paddle attachment, beat butter on medium speed until smooth and creamy, 1 to 2 minutes. Add sugar slowly, beating until combined. Scrape bowl. Beat in eggs one at a time, blending each one completely before adding each. Scrape bowl and blend in vanilla. On low speed, alternate adding dry ingredients and sour cream, adding flour in four parts and sour cream in three parts, beginning and ending with flour, and scraping bowl as needed.
Layer and marble batter and filling: Spoon 2 cups of batter into prepared pan. Smooth with back of big spoon, spreading batter to side of pan first and then to center. Sprinkle 1/2 cup filling evenly over batter. Cover filling with about 2 cups batter, dropping chunks around pan and smoothing with spoon. Sprinkle another 1/2 cup filling evenly over batter and cover with 2 more cups batter. Layer on another 1/2 cup filling and then remaining batter. (four layers of batter and three layers of filling.) Insert table knife 1 inch from side of pan straight into batter going almost to bottom. Run knife around pan two times, without lifting up blade, spacing circles about 1 inch apart. Smooth top with the back of spoon.
Top and bake the cake: Take a handful of streusel crumbs and squeeze firmly to form a large mass. Break up mass into smaller clumps, distributing streusel evenly over batter. Repeat with remaining streusel. Clump reserved chocolate filling mixture together with your hands and sprinkle over streusel. Press both toppings lightly into surface of cake. Bake until top of cake is golden brown, sides are beginning to pull away from pan, and skewer inserted into center of cake comes out clean, 70 to 75 minutes. Transfer to wire rack and let cool for an hour before removing from pan.