Preheat the oven to 350°F (180°C). Generously grease a 12-cup Bundt pan, making sure to coat every crevice, then dust it lightly with flour and tap out the excess.

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

In a large mixing bowl, beat the butter for about 2 minutes, until smooth and creamy. Add the sugar and the vanilla bean seeds, if using, and continue beating for about 3 minutes.

Add the oil and keep beating until the mixture becomes pale, light, and fluffy.

Add the eggs one at a time, mixing well after each addition and scraping down the sides of the bowl as needed. Along with the final egg, add the vanilla bean extract or vanilla bean paste.

Mix in the sour cream. Add half of the dry ingredients and mix on low speed just until combined. Pour in the milk and mix until incorporated. Add the remaining dry ingredients and mix only until no dry streaks remain, being careful not to overmix.

Transfer the batter to the prepared Bundt pan and smooth the top with a spatula. Bake for 45 to 60 minutes, or until the cake is golden and a toothpick inserted into the center comes out clean or with a few moist crumbs attached.

While the cake is baking, prepare the vanilla bean syrup. Combine the sugar, water, and vanilla bean seeds, if using, in a small saucepan over medium heat.

Bring the mixture to a gentle simmer, stirring occasionally, just until the sugar has completely dissolved. Remove from the heat and keep warm.

If using vanilla extract instead of the seeds, simply add the extract after you remove the syrup from the heat.

Once the cake is out of the oven, let it cool in the pan for 5 minutes. Using a skewer or toothpick, poke holes all over the exposed surface of the cake. Slowly spoon or brush the warm syrup over the cake, allowing it to soak in gradually. Let the cake cool in the pan for another 15 minutes before carefully inverting it onto a wire rack. Allow the cake to cool completely before glazing.

To make the white chocolate vanilla bean ganache, place the chopped white chocolate in a heatproof bowl. In a small saucepan, heat the heavy cream with the vanilla bean seeds (or paste) until steaming but not boiling. Pour the hot cream over the white chocolate and let it sit undisturbed for 1 minute. Whisk gently until smooth, glossy, and fully emulsified.

Allow the ganache to sit at room temperature for about 60 minutes, stirring occasionally, until it thickens to a pourable consistency. Once the cake is completely cool, pour the ganache over the top, letting it drip naturally down the sides before serving.

If the ganache is too runny, you can place it in the fridge for about 5 minutes. Stir gently. Then let it rest on the counter for 10 minutes before pouring over the cake.

These white chocolate curls make a beautiful garnish for the cake. For extra vanilla flavor, you can add the seeds from 1 vanilla bean to the melted chocolate, but this is completely optional.

Place the white chocolate and vegetable shortening in a heatproof bowl. Microwave in short intervals, stirring frequently, until smooth and fully melted. If using vanilla bean seeds, stir them in now.

Spread the melted chocolate into a thin, even layer on the back of a quarter sheet pan. This amount of chocolate is enough to cover a quarter sheet pan perfectly. If using a half sheet pan, spread the chocolate over only half of the surface so the layer is thick enough to create curls. The pan needs to be big enough to fit the freezer.

Freeze for four minutes, just until the chocolate loses its shine and feels firm but still slightly pliable when touched. If the chocolate becomes too hard, let it sit at room temperature for a minute or two before continuing.

Using a bench scraper, gently push the chocolate forward to create curls of varying sizes. Transfer the curls to a baking sheet lined with parchment paper as you work. If the chocolate becomes too soft, return it to the freezer briefly and continue. Also place the curls in the freezer if they are too soft, so they don’t lose shape.

While forming the curls, if they are breaking, that means the chocolate is too cold. If the curls are coming out in big chunks, it's too warm and the pan needs to go back in the freezer.

Once all the curls have been formed, chill them until firm. Store them in the freezer until ready to decorate the cake.