Shuck the corn and cut the kernels off the cobs. Keep the cobs to infuse the milk.

In a medium saucepan, combine milk, cream, and corn kernels, then add the cobs. Heat over medium heat until just simmering, then turn off and let steep for 30 minutes.

In a large bowl, whisk together egg yolks, sugar, and salt until thickened and pale.

Gradually add 1 cup of the warm corn-milk mixture to the egg yolks (tempering), then pour back into the saucepan. Stir in cornstarch slurry (if using) and cook until thickened, about 5-7 minutes.

Remove from heat, add vanilla bean seeds (or extract).

Remove the corn cobs and choose whether to leave the corn kernels in for texture or blend for a smoother result.

Chill the mixture for at least 4 hours, then churn in an ice cream maker according to instructions.

Transfer to a freezer-safe container, press parchment paper directly on the surface, cover, and freeze for at least 4 hours.