Preheat the oven to 325 F, and position a rack in the center of the oven. Thoroughly grease a 12-cup bundt pan with nonstick baking spray (or use your favorite go to combination of butter/shortening and flour to grease and dust the pan, getting it in all the nooks and crannies.)
Use a microplane zester to zest your lemons. You'll be using the lemon zest, as well as the juice from your lemons, and you'll need approximately 2 large lemons or 4 small lemons to get enough zest and juice.
In the bowl of your stand mixer fitted with the paddle attachment, combine the sugar with the lemon zest. Use your fingers to rub the lemon zest into the sugar until very fragrant.
Add the butter and cream cheese, and beat on medium speed (#4-6 on a Kitchen Aid mixer) for 7 minutes. Scrape the bowl down several times while mixing.
Beat in the eggs, 1 at a time, beating in each egg on medium speed for 1 full minute before adding the next egg. Add the vanilla.
In a bowl, sift together the flour, salt and baking powder. Separately, stir together the milk and lemon juice; the mixture will curdle. With the mixer on low, add the flour mixture in 3 additions, alternating with the lemon milk, starting and ending with the flour. Increase speed to medium and beat for 15 seconds.
Spread the batter into the prepared bundt pan. Bake for about 50-55 minutes, until a cake tester inserted in the cake comes out clean or with moist crumbs clinging to it.
Set the pan on a cooling rack, and cool for 15 minutes. Invert the cake onto the cooling rack, remove the pan, and cool the cake for an hour or two, until the cake is just warm or room temperature.