In a large, heavy saucepan, add the milk and the cream for a richer fromage blanc. In a mixing bowl, combine the buttermilk and lemon juice and stir to combine well. Add the buttermilk-lemon juice mixture to the milk and begin to heat the milk, over low heat and very slowly, to 175 degrees F. While the milk is heating, stir only twice, making 2 strokes each time, with a heat-proof spatula or other flat utensil. Check the temperature often. As soon as the temperature reaches 175 degrees F, remove the pot from the heat and allow to sit, undisturbed, for 10 minutes.
Line a large colander with 2 layers of fine cheesecloth and set over a large bowl. Gently ladle the curds and whey into the colander and allow to drain until the drips of whey slows, about 2 minutes. Tie the corners of the cheesecloth together to form a hanging pouch, and hang pouch over a bowl and allow to drain until the cheese reaches the desired consistency.
Serve as is, with preserves, honey or fresh fruit, or add salt or fresh herbs, to taste, and enjoy as a savory appetizer. If a rich cheese is desired, spoon or pour a bit of heavy cream over the top before serving. Also, if a very smooth product is desired, beat the cheese briefly with an electric mixer before serving.
Refrigerate until ready to serve, up to 1 week. If cheese is marinated in oil with fresh herbs, it will keep, refrigerated, for up to 1 month.