An increasing amount of sociolinguistic research has been concentrated on diachronic idiolect change: the change of an individual’s dialect over time. This paper adds to this growing topic by analyzing the English idiolect change of Giada De Laurentiis, a heritage speaker of Italian. The study analyzes De Laurentiis’ LOT, START, and GOAT vowels, as well as the voice onset time (VOT) of voiceless stops [k] and [p] by measuring the utterances of the code-switched word ‘mascarpone’ across 20 seasons on television. The data reflect the influence of L2 US English (rhoticity, diphthongization, lengthened VOTs) on heritage Italian in De Laurentiis’ idiolect.