Method 1: Separating egg whites and yolks for a lighter texture

1. Pre-heat oven to 325F (conventional / no fan) and prepare a 10" (12 cup) Bundt pan by brushing it with butter and dusting with flour
2. Separate the 5 eggs into whites and yolks and set aside
3. Add the flour, 2 cups sugar, baking powder and salt to the bowl of your stand mixer. Whisk to combine and remove any lumps
4. Add the room temperature butter and cream cheese to the bowl. Use the balloon whisk attachment to whisk on medium-low speed for 60-90s until the ingredients are combined and no streaks of dry flour remain. The mixture will resemble clumpy wet sand, or a scraggly dough
5. In a separate bowl, whisk together the egg yolks, oil, sour cream, vanilla and lemon zest until combined
6. Add the egg yolk mixture to the cake batter. Whisk on medium low speed for ~2 minutes until the ingredients are combined, and the batter becomes smooth and fluffy.  Scrape down the edges of the bowl once in the middle to ensure everything mixes properly. The batter will still be quite thick; do not overmix
7. Separately, in a clean bowl with a clean whisk, whisk the egg whites with the remaining 1/2 cup sugar on medium speed for a few minutes until they form a stiff, glossy meringue
8. Add the meringue to the cake batter in 2 additions, and use a rubber spatula to very slowly and gently fold it in. The result will be a smooth, fluffy and light cake batter
9. Transfer the cake batter to the prepared Bundt pan and spread it out evenly
10. Bake for 60-70 minutes at 325F until a toothpick inserted in the middle of the cake comes out with light, moist crumbs (no wet batter)
11. Remove the pan from the oven and let it cool down for 15-20 minutes. Then carefully turn out the cake onto a cake stand and let it fully cool down
12. Optionally, dust with icing sugar. Slice, serve and enjoy! 

Method 2: Keeping eggs whole for quicker recipe

1. Pre-heat oven to 325F (conventional / no fan) and prepare a 10" (12 cup) Bundt pan by brushing it with butter and dusting with flour
2. Add the flour, all of the sugar, baking powder and salt to the bowl of your stand mixer. Whisk to combine and remove any lumps
3. Add the room temperature butter and cream cheese to the bowl. Use the balloon whisk attachment to whisk on medium-low speed for 60-90s until the ingredients are combined and no streaks of dry flour remain. The mixture will resemble clumpy wet sand, or a scraggly dough
4. In a separate bowl, whisk together the eggs, oil, sour cream, vanilla and lemon zest until combined
5. Add half of the egg mixture to the cake batter and whisk it for 30 seconds on medium low speed. Then add the remaining half, and whisk on medium low speed for ~2 minutes until the ingredients are combined, and the batter becomes very smooth, light and fluffy.  Scrape down the edges of the bowl once in the middle to ensure everything mixes properly. Do not overmix!
6. Transfer the cake batter to the prepared Bundt pan and spread it out evenly
7. Bake for 60-70 minutes at 325F until a toothpick inserted in the middle of the cake comes out with light, moist crumbs (no wet batter)
8. Remove the pan from the oven and let it cool down for 15-20 minutes. Then carefully turn out the cake onto a cake stand and let it fully cool down
9. Optionally, dust with icing sugar. Slice, serve and enjoy!

Video tutorial: