Heat large, flat bottom skillet or griddle over medium heat. Add coconut oil, melt, and swirl around pan.
Whisk together egg and heavy cream. Press piece of bread into mixture, flip, and place in skillet. Repeat with remaining pieces of bread. Cook on each side until golden brown.
To make banana topping, melt butter in a skillet over low heat. Stir in cinnamon, bourbon, sugar and scrape in the vanilla bean seeds, cook for 30-60 seconds until sugar has dissolved. Add in sliced bananas and stir to coat. Cook for 1-2 minutes until bananas are hot. Pour in the heavy cream, continuing to cook until topping is warm, 1-2 more minutes.
Serve french toast with a spoonful of bananas and sprinkle of walnuts.