Preheat oven to 350°.
In a non-reactive bowl, whip egg whites and sugar until fluffy. Add olive oil into egg white and sugar mixture. In a separate bowl, sift flour, baking powder and salt together. Alternate folding flour mixture and buttermilk into egg white mixture until fully incorporated.
Pour combined olive oil cake mixture into a greased Bundt pan and bake for 30 minutes or until golden brown and firm to the touch.
For the sabayon sauce, whisk egg yolks, sugar, and chardonnay in a medium stainless steel bowl. Place bowl over a pot of simmering water (the bowl should not touch the water or the eggs will heat too quickly), whisking constantly until the sugar dissolves and the sauce begins to thicken (about 5 minutes.) Transfer to a mixer and whip until cool and fluffy.
In separate bowl whip crème fraiche and heavy cream to stiff peaks. Gently fold into sabayon egg mixture to combine.
To serve, dust olive oil cake with powdered sugar and spoon sabayon sauce over individual cake slices.