While the US is in fact known as the manufacturers of several delicious varieties of cookie, you might be surprised to learn that consumer packaged goods as a whole are not among the top 10 categories of goods exported from the US to the UK. So I'm not sure supermarket shelves are a great data point.
(Total US->UK ~$55bn, about 4% of total US exports, top categories: aircraft, oil, cars, machinery, electronics.)
(Total US->UK ~$55bn, about 4% of total US exports, top categories: aircraft, oil, cars, machinery, electronics.)