Preheat the oven to 350°F. Grease a 9×13-inch glass or ceramic baking dish with softened salted butter.
In a medium bowl, whisk together the fine yellow cornmeal, all-purpose flour, granulated sugar, fine sea salt, and baking powder.
Add the eggs, whole milk, heavy cream, melted butter, vanilla extract, and lemon zest to a blender. Blend for 20 to 30 seconds, until smooth.
Add the dry cornmeal mixture to the blender. Blend for 30 to 45 seconds, or until fully combined.
Pour the thin batter into the prepared baking dish. Tap the dish gently on the counter to release large air bubbles.
Bake for 55 to 65 minutes, or until the top is golden, the edges are set, and the center has a slight jiggle.
Remove from the oven and cool on a wire rack for at least one hour.
Dust with powdered sugar, slice into squares, and serve warm, room temperature, or chilled.