Little if any literature is available on the functionality of gluten proteins in yeast leavened developed dough systems containing high sugar and fat levels. We here studied whether and to what extent gluten proteins impact the different phases of the production of such a system (which contains about 35 parts invert syrup and 70 parts margarine per 100 parts flour) and how these proteins affect its quality. In a first approach, we used model systems based on gluten–starch blends as this allowed specifically altering the gluten levels without altering the gluten quality and/or levels of other wheat flour components. In a second approach flour was heat treated upfront to alter its gluten proteins. Despite the large amounts of sugars and fat, the presence of a developed gluten network in these systems allowed dough pieces to retain gas during fermentation. Also, dough pieces with a developed gluten network could expand faster during subsequent baking than dough pieces without a developed gluten network (i.e. ca. 3.6 vs. 1.9cm/min, respectively). Remarkably, at a given moment during baking (i.e. between 65 and 105sec of baking), dough pieces started to shrink in all directions. This was related to the (elastic) protein network present in the system. However, the time at which shrinking occurred was influenced by factors other than the gluten network. Besides the level, the quality of the gluten fraction determined gluten development during mixing of dough systems containing high levels of sugars and fat, and thus, the spread behavior during fermentation and baking and the final product's dimensions.