Sure, I've got a few suggestions that should work well in this Italian cake recipe.  My favorite ricotta substitute is small-curd cottage cheese. It has a similar texture, mild taste, and fat content that won't overpower the delicate flavors of the cake. Just make sure to blend or puree the cottage cheese until smooth before incorporating it into the batter to help it blend seamlessly. Another option is cream cheese. It's richer and denser than ricotta, but it *should* still work here. Be sure to soften the cream cheese and beat it well to remove any lumps before adding it to the batter. Cream cheese also has a slightly tangy taste, so it might add a little extra je ne sais quois to the final flavor of your cake. If you prefer a dairy-free alternative, you can also try using silken tofu. While it won't provide the same flavor profile as ricotta, it'll likely have a similar effect on the bake, giving it a soft and moist texture. Be sure to blend the silken tofu until smooth to give it the proper ricotta-like consistency we're after. Keep in mind that the taste may vary slightly with any of these substitutions, so you might want to taste the batter before baking and make any necessary adjustments by adding a bit more lemon juice or sugar, as per your preference.