Preheat oven to 350 degrees.
For crust: Preheat oven to 350 and prepare 8 or 9 inch spring form pan (or deep dish 9 inch pie plate). In a food processor, crush crackers and measure out 1 1/4 cup. Return crumbs to processor, add sugar, pulse until evenly blended. Add egg white and pulse until moistened. Bake at 350 for 8-10 minutes until golden.
Turn oven down to 325 degrees for cheesecake.
Allow pie crust to cool while combining condensed milk and cream cheese (very important for ingredients to be at room temperature) on low to medium-low speed just until smooth, scraping down sides if needed. Sprinkle in cornstarch careful to be sure that it is evenly distributed. Add eggs, egg beaters, vanilla, lemon zest and lemon juice and combine on low speed until smooth - be careful not to overmix - scraping down the sides if needed.
Pour into pie crust, but don't go over the edge (it will puff some and then deflate while cooling). If bubbles appear on surface, run knife through cheesecake and pop any visible bubbles.
IF you have extra filling (if using a pre-made crust, you definitely will have leftover filling - this depends on size of your pie plate), spray ramekin with non-stick spray and bake 40 minutes, checking visually every 5 minutes after 30 minutes has gone by.
Bake for 40-45 minutes (or more depending on your oven) until edges are just brown or tiny cracks appear on edges of cake and center does not jiggle when you shake the pan. Don't open the oven door more than necessary!
Turn oven off and prop door open and allow cheesecake to cool for 30-45 minutes in oven. Transfer to wire rack and cool completely. Chill in fridge overnight or a minimum of three hours,. If using spring form pan, remove edges just before serving.