Preheat the oven to 350°F (175°C). Spray a loaf pan with non-stick baking spray or line with parchment paper.

In a medium mixing bowl, whisk together the flour, cornstarch, baking powder, and salt. Set aside.

In a mixing bowl, combine sugar and lemon zest, and mix for 1 minute.

Add room temperature butter to the sugar mixture and cream for 3-4 minutes.

Add the eggs and extra yolk one at a time, beating after each addition.

Mix in the canola oil, lemon juice, and vanilla extract until well combined.

With the mixer on low, add half of the flour mixture, followed by the half and half, then the rest of the flour mixture, mixing until just combined.

Scrape the bottom of the bowl to ensure all ingredients are mixed well, then spread the batter into the prepared loaf pan.

Bake for 45-50 minutes until the top is golden brown and a toothpick comes out with a few moist crumbs.

Let the loaf cool in the pan for 10-15 minutes, then remove from pan and place on a cooling rack to cool completely.

In a small bowl, mix the powdered sugar, lemon juice, and half and half until smooth.

Serve the loaf in thin slices. For a balanced snack, pair a slice with Greek yogurt or cottage cheese.