Steps

• 1-

  For the cake: Preheat the oven to 350 degrees F. Coat a 9-by-13-inch baking pan with nonstick cooking spray. Line the bottom of the pan with parchment and coat again with the spray.

• 2-

  Whisk together the flour, oats, granulated sugar, brown sugar, cinnamon, baking powder, salt and baking soda in a large bowl and set aside. Whisk together the oil, buttermilk, vanilla and eggs in a medium bowl. Fold the buttermilk mixture into the flour mixture until just combined.
  

• 3-

  Pour the batter into the prepared pan and bake until a toothpick inserted in the center comes out clean, about 35 minutes.

• 4-

  For the glaze: Meanwhile, add the brown sugar, oats, coconut, butter, milk, cinnamon and salt to a small saucepan over high heat. Bring to a boil and cook until the butter and sugar are dissolved, about 1 minute. Turn off the heat and stir in the pecans.

• 5-

  Pour the hot glaze over the warm cake and spread evenly. Let the cake cool in the pan on a rack until cooled completely, at least 40 minutes. The glaze will still look glossy but should be not be sticky. You can cut slices from the pan or invert onto a serving platter or cutting board. Store at room temperature for up to 1 week.