Homemade Butter and Buttermilk

Transfer cream to bowl of 5-quart electric stand mixer fitted with whisk attachment. Tightly cover top of bowl and mixer with plastic wrap. Beat cream at moderately high speed until it holds soft peaks, 10 to 12 minutes. Increase speed to high and beat until mixture separates into thick, pale-yellow butter and thin, liquid buttermilk, about 5 minutes more. Strain mixture through colander into large bowl. Using hands, vigorously knead butter in colander, squeezing out remaining buttermilk, until dense and creamy, about 5 minutes. Transfer butter to large bowl, reserving buttermilk. Using hands, knead salt into butter. Roll into logs and wrap in plastic wrap or transfer to airtight container and refrigerate. (Butter will keep up to 1 week refrigerated or 1 month frozen.) Strain buttermilk through fine-mesh sieve, then cover and refrigerate up to 1 week.