Preheat the oven to 325°F. Grease well and line with parchment a 9-inch round cake pan.

In a mixing bowl, beat the eggs, sugar, vanilla, lemon zest, and orange zest until thick and light, about 5 minutes.

With the mixer on medium-low, slowly drizzle in the olive oil. Raise the speed and beat until emulsified, about 1 minute. Scrape the bowl and stir, making sure the batter is evenly mixed. PRO TIP: This is the most important part to get right! Make sure that the olive oil is emulsified into the batter. If you see an oil slick on the top, scrape the bowl and keep beating.

Add the flour, cornmeal, baking powder, and salt. Mix on low until fully combined. Scrape the bowl again and make sure the mixture is properly stirred together.

Pour the polenta cake batter into the cake pan. Bake for 55 to 60 minutes, or until a cake tester comes out clean. Do not overbake.

When cool enough to handle, run a thin knife or offset spatula around the edge of the cake pan to loosen the cake from the sides. Turn the cake onto a cooling rack and cool. PRO TIP: I often keep this cake upside down and serve it that way. The top will be flatter and have fewer crumbs.

Whisk together the powdered sugar and 2 tablespoons fresh orange juice (from ½ orange) and 2 tablespoons lemon juice (from one lemon). The glaze should be thick but pourable.

Pour the glaze over the cake, and use an offset spatula or knife to spread it evenly, ideally letting some of the glaze drip over the edges.PRO TIP: Place a sheet of parchment beneath the cake or cooling rack to "catch" any glaze that drips off of the cake for easy cleanup.

Decorate the top of the cake with a slice of orange or two right before serving if you'd like. Serve at room temperature.