What is the recipe for butter sake sauce?

I have the recipe for the Cheesecake Factory Miso Salmon, however I do not have the recipe for the butter sake sauce.

Sake Butter
In a small saucepan over medium-high heat, sweat the ginger and shallots in the one tablespoon butter for two to three minutes.
Add 1/2 cup of the sake, bring to a boil, and reduce by two-thirds, about three minutes.
Add the heavy cream, bring to a boil, and reduce by half, about two minutes.
Add the pieces of cold butter to the sauce, bit by bit, whisking constantly over medium-high heat. The butter will emulsify, creating a thick creamy sauce.
Once all the butter has been incorporated, remove the pan from the heat. Whisk in the remaining one teaspoon sake and the lime juice.
Season to taste with salt.

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