1 and ½ cups (packed) golden brown sugar
1 tablespoon ground cinnamon
6 tablespoons (3/4 stick) chilled salted butter, diced
1 and ½ cups coarsely chopped pecans
1 cup semisweet chocolate chips
3 cups AP flour
1 and ½ teaspoons baking soda
1 and ½ teaspoons baking powder
1 and 1/3 cups sugar
¾ cups (1 and ½ sticks) salted butter at room temp
1 and ½ teaspoons grated orange peel
1 and ½ teaspoons vanilla extract
1 and ½ cups sour cream
¼ cup orange juice
Powdered sugar for dusting
Whisk brown sugar and cinnamon in medium bowl to blend; add butter and rub in with fingertips until mixture holds together in small, moist clumps. Mix in pecans and chocolate chips. (can be made 3 days ahead. Cover and refrigerate).
Preheat oven to 350 degrees Fahrenheit. Grease and flour a 13x9x2-inch metal baking pan. Sift flour, baking soda, baking powder into medium bowl. Using electric mixer, beat sugar and butter in a large bowl until blended and smooth. Beat in eggs one at a time, then orange peel and vanilla extract. Mix in flour mixture in 4 additions alternately with sour cream in 3 additions. Mix in orange juice. Spread half of the batter in prepared pan. Sprinkle with half of the streusel. Drop remaining batter over by heaping tablespoonfuls; carefully spread batter to make even layer. Sprinkle with remaining streusel.
Bake cake for 30 minutes. After 30 minutes, lay a sheet of foil loosely over pan and bake for an additional 35 minutes or until tester inserted into center of cake comes out clean. Remove the foil and allow the cake to cool in the pan on rack (about 20minutes). Dust with powdered sugar; serve warm or at room temperature (can be made 2 days ahead; cool completely and store airtight at room temp).
Yields 12 servings