Preheat oven to 350 degrees F.  Oil a 9 by 13 inch baking pan.

In a large bowl, whisk together oil, banana, and eggs until well combined.  Stir in flour, baking soda, vanilla powder, and poppy seeds.

Spread into the prepared pan and bake about 25 minutes until golden brown and a toothpick inserted in the center comes out clean or with a few moist crumbs.  Serve warm or cool completely in the pan.  Cake may be stored in an airtight container at room temperature for up to 3 days or frozen, wrapped in parchment and foil and placed in a zipper bag, for up to 3 months.  Thaw at room temperature about an hour or in the microwave about 30 seconds.