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Throwing all ingredients into a pot simultaneously causes the dairy to curdle upon contact with the acidic tomatoes. Acidic environments destabilize dairy proteins rapidly when exposed to high heat. Tomatoes possess a high level of natural acidity, registering around pH 4.0 to 4.5. Heavy cream and butter require gentle treatment to maintain a smooth emulsion rather than breaking into oil droplets and solid curds.
Multiplying this recipe requires careful attention to the ratio of crushed tomatoes to chicken broth. Doubling the batch does not require doubling the simmering time, as surface area increases in wider pots. Monitor the liquid reduction visually rather than relying strictly on the initial ten-minute timer. Retain the exact proportion of sugar, which offsets the sharp acidity of 56 ounces of canned tomatoes without adding noticeable sweetness. Fresh basil leaves lose volatile aromatic compounds rapidly when subjected to prolonged boiling. Mince the eighteen to twenty leaves finely and stir them in just before the dairy phase to preserve their herbal punch. When scaling down for fewer servings, reduce the heat to the lowest possible setting before incorporating the butter. High heat will scorch dairy solids at the bottom of a thin stainless steel saucepan.