Beat cream cheese and 1 1/4 cups of the granulated sugar with a stand mixer fitted with a paddle attachment on medium speed until just smooth, about 1 minute. Scrape down sides of bowl using a rubber spatula. Add sour cream, vanilla, and 1 tablespoon of the lemon zest, beating until just combined, about 1 minute. Add eggs 1 at a time, beating on low speed until combined, about 30 seconds. Do not overbeat.