In the bowl of a mixer fitted with a paddle attachment, combine eggs and sugar. Beat on medium-high speed until light in color, about 4 minutes. Add vanilla, olive oil, lemon zest, and lemon juice.
In a separate bowl, sift together flour, baking soda, and salt. Add to egg mixture, along with polenta. Mix until combined.
Pour two thirds of batter into prepared pan, and completely cover it with cherries. Spoon remaining batter over cherries, allowing fruit to peek through in spots. Bake until top and edges are lightly golden and a toothpick (or fork) inserted in the center comes out clean, 1 hour to 1 hour 15 minutes. Remove from oven and cool pan on a wire rack for 10 minutes. Remove cake from pan and cool completely on rack. Cut cake, and serve each slice with a dollop of crème fraîche.
Adapted from The Paley's Place Cookbook, by Vitaly Paley and Kimberly Paley with Robert Reynolds, copyright © 2008 (with permission from Ten Speed Press).