Consumers are always searching for food preparations that make their lives easier. Powdered cake mixes, for example, often contain high levels of digestible carbohydrates and are low in protein, compromising their nutritional value. This study aimed to develop a powdered cake mix for microwave baking with increased fiber and protein content, using a simplex centroid design to optimize the mixture of wheat flour (WF), isolated soy protein (ISP), and oat flour (OF). The response variables analyzed included specific volume, hardness, adhesiveness, elasticity, cohesiveness, gumminess, chewiness, and resilience. The optimized formulation, consisting of 35% WF and 65% of a blend of ISP and OF (78% OF and 22% ISP), resulted in a 28% increase in protein content and a 7% increase in dietary fiber compared to the standard mix. ISP had a greater impact on hardness (ß_x21786.4) and chewiness (ß_x21274.7), while OF contributed more subtly (ß_x3700.4 and ß_x3499.2, respectively). Response surfaces showed that adding ISP and OF altered volume and texture, but OF led to fewer textural changes. Oat-based ingredients are gaining attention due to their health benefits, as β-glucan from oats has recognized health claims, while vegetable proteins like ISP contribute to higher protein intake. Though the texture of the optimized cake remained comparable to the standard version, sensory analysis is necessary to confirm consumer acceptance of formulations. In conclusion, the soy protein and oat fiber chocolate cake mix balances improved nutritional value with satisfactory textural qualities and offers a practical, healthier alternative for quick and easy food preparations.