Blend in sweetened condensed milk, lemon juice, and lemon extract.
Pour into a loaf pan or any freezer safe dish and freeze until solid - about 4+ hours.
I used lemon zest when I made this recipe, but it's so easy to substitute with lemon extract. If you don't want the texture of the lemon zest, use extract instead! It's a powerful flavor substitute. (Generally, you'll use half the amount of the measurement suggested for zest. In this situation, that would be 1 tablespoon of extract vs. the 2 tablespoons of zest.)