What's for dessert: Low-carb ricotta cheesecake

I had some ricotta hanging around the fridge, and thought that maybe it could make a semi-healthy cheesecake (at least for those of us on low-carb diets).  I’ve heard of them before and to me it’s a pretty simple formula.  I beat two eggs and one egg yolk with ½ cup of granulated Splenda, 1 t vanilla, the zest of one lemon, and three cups of low-fat ricotta.  We have three small springform pans and I thought they’d make nice four-serving cakes.  Just sprayed them with some cooking spray and divided the batter between them.  Into a 325 oven for 20 minutes, then 225 degrees for 40 minutes.  About 20 minutes before they were done I spread each with some of a combination of 1 C sour cream, 1 T lemon juice, and 1 T granulated Splenda.   Next time I will wait until the cheesecakes are a little firmer before I do that because some of the sour cream mixture sank down into the middle of them.  However, they are good anyway.