Set a rack in the middle of the oven and preheat to 350°F / 180°C. Generously butter a 12-cup / 2.8L Bundt pan, then dust it with a thick layer of flour. In a stand mixer fitted with the paddle, beat the butter, flour, cornmeal, granulated sugar, brown sugar, cardamom, baking soda, and salt on medium-low speed until fully combined, about 2 minutes. Scrape down the bottom and sides of the bowl. Gradually add the whole eggs and egg yolks and beat, scraping the bowl as needed, until fully incorporated. Scrape the bowl, then beat for 15 seconds more. Gradually add the buttermilk, followed by the canola oil, and beat until fully incorporated. Pour the batter into the prepared pan, smoothing the top. Bake until the top is lightly golden and a skewer inserted near the center of the cake comes out clean, 45 to 50 minutes. Be careful not to overbake this cake or it will dry out! Let the cake cool in the pan on a wire rack for 30 minutes. Carefully zip the pan onto the rack and tap it to make sure the cake is released. Remove the pan and let the cake cool completely.
DIRECTIONS FOR THE ROSE WATER GLAZE
Sift the powdered sugar into the bowl of a stand mixer, then add the rose water and use the whisk attachment to mix on low speed for 15 seconds. Scrape the bowl, then add the milk, lemon zest, and salt and whip on medium-high speed for 30 seconds. If the glaze seems too runny, let it stand for a few minutes to firm up. Place the cake on a wire rack set inside a baking sheet. Transfer the glaze to a small, spouted measuring cup, then slowly pour it over the top of the Bundt, using a small spoon to scoop the glaze onto the cake as needed so it drizzles down the sides. Before the glaze sets, sprinkle the cake with dried rosebuds and rose petals and let set for a few minutes before serving. The cake keeps covered in the refrigerator for up to 1 day.