Preheat oven to 350 degrees. Butter a 9 inch spring form pan and set aside.
In the bowl of a standing mixer (or in a bowl with a handheld mixer) beat eggs until a bit frothy. Add sugar and beat until combined.
Add yogurt to egg-sugar mixture; beat to fully combine. Slowly drizzle olive oil into egg-sugar mixture while beating on medium speed to allow oil to fully integrate to egg-sugar mixture.
In a separate bowl stir to combine flour, almond flour, cornmeal, baking powder, and salt. With mixer at medium speed, spoon flour mixture into the egg-sugar-oil mixture a large spoonful at a time, allowing it to combine before adding more flour.
Once combined add diced sage and mix just to combine. Do not over mix.
Pour into prepared pan and bake for 30-35 minute (until lightly browned on top and toothpick comes out clean). Remove from oven and allow to cool before releasing the sides of the pan to cut and serve.
Making the Glaze
Combine the confectioner’ sugar and port wine. Whisk to fully combine leaving no lumps of sugar.
Lightly drizzle on cooled, room temperature cake. Suggested drizzle method: use a squeeze bottle with a cone top to more precisely drizzle the glaze over the cake slices.
To serve: Sprinkle with chopped pepitas and serve with red grapes.