- Preheat oven to 350 degrees F. Adjust rack in oven to middle.  
- Grease or spray the inside of a 10" tube pan. Whisk dry ingredients together; flour, baking powder, baking soda and salt. 
- In a stand mixer fitted with paddle attachment, beat butter and 1 cup plus 2 Tablespoons sugar, and lemon zest together until light and fluffy, scrapping down sides of bowl as necessary, about 3 minutes. 
- Add eggs, one at a time, beating well after each addition, about 20 seconds. Scrape down sides of bowl. Add 4 teaspoons vanilla, mixing to combine. 
- Reduce speed of mixer to low, add 1/3 flour mixture and 1/2 sour cream, mixing to blend, just until combined about 5 to 10 seconds. Repeat with 1/3 flour mixture and remaining sour cream, mixing just until combined. Add remaining 1/3 flour and mix for 10 seconds. Use a rubber spatula and make sure all of the flour is combined.  
- Reserve 1/4 cup batter and pour 1/2 cup batter into the tube pan. Reserve remaining 1/2 cup, in addition to the 1/4 cup batter. 
- No need to rinse out mixing bowl. Beat cream cheese, 5 Tablespoons sugar, lemon juice, and remaining 1 teaspoon vanilla on medium speed until light and smooth. Fold in 1/4 cup batter. Mixing until smooth. 
- Drop cream cheese mixture into tube pan, avoiding edges of pan and smooth with an offset spatula. 
- Spread remaining 1/2 cup batter and spread over cream cheese filling. Using an offset spatula to swirl the filling into the cake, avoiding edges and sides of pan. Rap or drop cake pan 2 or 3 times to dislodge any bubbles. 
- Bake at 350 degrees for 45-50 minutes or until a long stick inserted in the cake part (not the cream cheese part) comes out clean. 
- Cool cake in pan on wire rack for an hour. Remove cake from pan and cool top up another hour or until completely cool. 
- Wrap any remaining cake in plastic or an airtight container.