Step 1

Gently heat milk in a large saucepan over low, stirring occasionally, until an instant-read thermometer registers 80°. Remove from heat, add rennet, and stir to combine. Cover pot with a tight-fitting lid. Let rest in a warm place (so milk will maintain room temperature) until curd is set, looks like the texture of silken tofu, and is just beginning to pull away from sides of pot, 4–5 hours.

Step 2

Using a sharp knife and inserting into pot, cut curd vertically into 1" strips, then cut 1" strips horizontally to create a grid pattern. Let sit 5 minutes.

Step 3

Line a colander with 2 layers of cheesecloth.

Step 4

Return pot to very low heat (as low as possible) and add 2 tsp. salt. Gently stir with a wooden spoon to break up curds. Continue to cook, stirring once every 5 minutes, until instant-read thermometer inserted into center of curds registers 115°, about 15 minutes.

Step 5

Pour curds into prepared colander set over sink and let drain until curds are room temperature, about 15 minutes. Transfer drained curds to a medium bowl. Add buttermilk, cream, and ¾ tsp. salt. Stir with a fork to break up curds and combine. Taste and add more salt if needed. Cover and chill at least 1 hour before serving.

Step 6

Do Ahead: Cottage cheese can be made 4 days ahead. Keep chilled.