In a saucepan, combine egg yolks, maple syrup (or cane sugar), lemon juice, and lemon zest. Cook over low heat, whisking continuously for about 10 minutes until the mixture thickens and coats the back of a spoon.

Remove from heat, strain through a fine mesh sieve, and whisk in butter until melted. Chill the lemon curd in the refrigerator for at least 1 hour to set the flavors.

In a large mixing bowl, blend together heavy cream, cane sugar, vanilla extract, and whole milk until smooth. Use an electric mixer on medium speed for about 3 minutes until the mixture is well combined and slightly thickened.

Once the lemon curd has chilled, gently fold it into the ice cream base using a spatula, aiming for a swirling effect rather than a complete mix.

Pour the combined mixture into an ice cream maker and churn according to the manufacturer's instructions, usually about 20-30 minutes until it reaches a soft-serve consistency.

Transfer the ice cream into a freezer-safe container, smoothing the top, and freeze for at least 4 hours or until firm.

Before serving, let the ice cream sit at room temperature for 5-10 minutes to soften slightly. Serve in bowls or cones.