Objective: To determine the health benefits and harms of various ingredients in Christmas desserts from The Great British Bake Off., Design: Umbrella review of umbrella reviews of meta-analyses of observational studies., Data Sources: The Great British Bake Off website, Embase, Medline, and Scopus., Inclusion Criteria: Umbrella reviews of meta-analyses of observational studies evaluating the associations between Christmas dessert ingredients and the risk of death or disease., Main Outcome Measures: Proportion of protective and harmful summary associations between ingredient groups from The Great British Bake Off Christmas dessert recipes and the risk of death or disease., Results: 48 recipes for Christmas desserts (ie, cakes, biscuits, pastries, and puddings and desserts) were provided on The Great British Bake Off website with 178 unique ingredients that were collapsed into 17 overarching ingredient groups. A literature search identified 7008 titles and abstracts, of which 46 eligible umbrella reviews reported 363 unique summary associations between the ingredient groups and risk of death or disease. Of these summary associations, 149 (41%) were significant, including 110 (74%) that estimated that the ingredient groups reduced the risk of death or disease and 39 (26%) that increased the risk. The most common ingredient groups associated with a reduced risk of death or disease were fruit (44/110, 40%), coffee (17/110, 16%), and nuts (14/110, 13%), whereas alcohol (20/39, 51%) and sugar (5/39, 13%) were the most common ingredient groups associated with increased risk of death or disease., Conclusions: Recipes for Christmas desserts from The Great British Bake Off often use ingredient groups that are associated with reductions, rather than increases, in the risk of death or disease. This Christmas, if concerns about the limitations of observational nutrition research are set aside, you can have your cake and eat it too., Competing Interests: Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/disclosure-of-interest and declare: no support from any organisation for the submitted work; JDW is supported by the FDA, Johnson and Johnson through the Yale Open Data Access project, and the National Institute on Alcohol Abuse and Alcoholism of the National Institutes of Health under award 1K01AA028258. JDW served as a consultant to Hagens Berman Sobol Shapiro LLP and Dugan Law Firm APLC. RR reported receiving research support from the Stavros Niarchos Foundation through Yale Law School for a project entitled Re-envisioning Publicly Funded Biomedical Research and Development and the US Food and Drug Administration for a project entitled Best Practices for Adequately Representing Women, Older Adults and Patients Identifying as Racial and Ethnic Minorities in Oncology Research: A Positive Deviance Approach; consultant fees for the ReAct-Action on Antibiotic Resistance Strategic Policy Program at Johns Hopkins Bloomberg School of Public Health, which is funded by the Swedish International Development and Cooperation Agency; and grant support from Arnold Ventures outside the submitted work. JSR reported receiving grants from the US Food and Drug Administration; Johnson and Johnson; Medical Device Innovation Consortium; Agency for Healthcare Research and Quality; National Heart, Lung, and Blood Institute; and Arnold Ventures outside the submitted work. JSR also is an expert witness at the request of relator attorneys, the Greene Law Firm, in a qui tam suit alleging violations of the False Claims Act and Anti-Kickback Statute against Biogen Inc that was settled in September 2022. The authors declare no other relationships or activities that could appear to have influenced the submitted work., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)