1. Make the Lemon Curd:

• In a heatproof bowl (or the top of a double boiler), beat the egg yolks for 1 minute.
• Add the maple syrup or cane sugar and beat for another minute.
• Add the lemon juice and lemon zest and mix well.
• Place the bowl over a pan of simmering water (make sure the bottom of the bowl doesn’t touch the water).
• Cook, stirring nearly constantly, until the mixture thickens, about 10-20 minutes. It should coat the back of a spoon.
• Stir in the butter, one piece at a time, waiting until each piece melts before adding another one.
• Remove from the heat and strain the curd through a fine-mesh sieve into a storage jar.
• Cool until just warm.
• Cover and refrigerate until set, at least 2 hours.

2. Make the Ice Cream Base:

• In a large mixing bowl, beat the heavy whipping cream, sugar, and vanilla extract with a hand mixer until the cream is thickened but not quite enough for dolloping. It should be a little liquid and not able to hold peaks.
• With the mixer on low speed, slowly pour in the whole milk and mix until well combined.

3. Churn the Ice Cream (Ice Cream Maker Method):

• Churn the ice cream mixture according to your ice cream maker instructions.

4. Add the Lemon Curd (Ice Cream Maker Method):

• Once the ice cream is done churning, scoop it into a freezer-safe storage container.
• Dollop half of the lemon curd over the top and fold it into the ice cream with a spatula.
• Dollop the remaining lemon curd over the top and fold in.
• Freeze for several hours, or until firm.

5. No-Churn Method: * Mix ice cream base and pour it into a freezer-safe container. * Freeze until firm but still able to be stirred, about 3 hours. * Fold in the lemon curd as described above. * Freeze until completely firm, several more hours.