01 -
Preheat the oven to 350° F and place a rack in the center of the oven.
02 -
Lightly grease a 9"x13" baking pan and set aside.
03 -
In a medium bowl, combine flour, brown sugar, granulated white sugar, and cinnamon; then add oil.
04 -
In a separate bowl take 3/4 cup of the flour mixture and add chopped nuts, set aside (for streusel topping).
05 -
Next, stir in baking powder and baking soda.
06 -
Mix in buttermilk and egg until just well incorporated.
07 -
Pour batter into baking pan and sprinkle with reserved streusel topping.
08 -
Bake for 35 minutes, or until a toothpick inserted in the center comes out clean.
09 -
Set aside for the cake to cool down for 5-10 minutes.
10 -
Cut, serve and enjoy!!!.