1Heat oven to 350°F. Spray bottom only of 9-inch square pan with cooking spray. In small bowl, mix streusel ingredients with fork until crumbly; set aside.
2In large bowl, mix flours, 3/4 cup brown sugar, the baking powder, baking soda and salt. Stir in remaining coffee cake ingredients until well blended.
3Spoon half of batter in pan, spreading evenly. Sprinkle 1/2 cup of the streusel evenly over batter. Drop remaining batter by spoonfuls over streusel; carefully spread. Sprinkle with remaining streusel.
4Bake 30 to 35 minutes or until toothpick inserted in center comes out clean. Cool about 1 hour. Serve warm.