In a medium saucepan, combine egg yolks, maple syrup, lemon juice, lemon zest, and butter. Over low heat, whisk continuously for about 10–15 minutes until thickened and coats the back of a spoon. Strain through a fine sieve into a bowl and let cool completely.

In a large bowl, whisk the heavy cream and cane sugar together until soft peaks form, about 3–5 minutes. Gradually add vanilla extract, then gently fold in whole milk until combined.

Pour half of the ice cream base into a mixing bowl, then spoon in half of the cooled lemon curd. Use a spatula to swirl gently, maintaining visible ribbons of curd.

Transfer the mixture into an airtight container, smooth the top, cover tightly, and freeze for at least 6 hours or overnight until firm.