Preheat your oven to 325°F. Generously spray a Bundt pan with baking spray or grease with butter, using a pastry brush to get the spray or butter into all the crevices. Set the pan aside.
Sift together the flour and baking soda into a large mixing bowl. Whisk in the salt and nutmeg and set the dry ingredients aside.
In a separate medium mixing bowl, whisk together the buttermilk, sour cream, lemon juice, and lemon zest, and set aside.
Add the butter to the bowl of a stand mixer fitted with the paddle attachment and beat on medium-high (7-8 on a stand mixer) for 2-3 minutes until light and creamy. Add the sugar to the bowl with the butter and beat on medium for 3-5 more minutes until the butter and sugar are light and fluffy. Be sure to scrape down the bottom and sides of the bowl to make sure the ingredients get evenly mixed.
Beat in the eggs and egg yolks one at a time at medium speed, making sure the eggs are completely mixed in after each addition.
Beat ⅓ of the flour mixture into the butter mixture just until no more dry flour is visible. Start on low speed and gradually increase the speed to medium. Beat in ½ of the buttermilk mixture. Scrape down the bowl and repeat this process, alternating beating in the flour and buttermilk mixtures until all have been incorporated. Mix in the vanilla bean paste. Be careful not to overmix the batter.
Pour the batter into the prepared Bundt pan and smooth it out into an even layer. Bake the cake in the preheated oven for 1 hour and 5 minutes to 1 hour and 20 minutes, or until a skewer inserted near the center comes out with just a few moist crumbs.
Allow the cake to cool for 10 minutes in the pan then carefully flip it out onto a wire rack to cool completely.
In a medium mixing bowl, whisk together the powdered sugar, lemon juice, and milk for the glaze and pour the glaze over the completely cooled cake. Slice and enjoy!