“Económicos” are traditional Portuguese pastry products; although their production is low-cost, their nutritional value is equally low. Since it is a widely consumed product in the Trás-os-Montes region, it is important to add value to it without making significant changes to the traditional recipe. Thus, this work has the main objective to increase the nutritional power of “económicos” through the incorporation of chestnut (Castanea sativa) fruit flour. The influence of the incorporation of 9% of chestnut flour as a new ingredient was analysed in terms of physical parameters (texture, colour, pH, water activity and moisture), nutritional content (according to the official AOAC methodology) and chemical parameters (sugars, fatty acids and organic acids) and the ability to control the microbial load over shelf life (32 days). Overall, the addition of the chestnut flour did not drastically change the appearance of the chemical and physical profiles of the cakes, but resulted in a lighter crumb (L*), slight changes in the texture profile, reduction of fat, and most importantly, introduced healthier flour to this inexpensive cake. Moreover, it did not stimulate the growth of microorganisms (total aerobic mesophiles, coliforms, Bacillus cereus, molds, and yeasts) during the 32 days of storage.