The influence of fat quantity and composition on the characteristics of a chemically leavened baked product was investigated, applying a central composite design combined with response surface methodology. Fats were blends of palm oil and palm olein with different slip melting points (from 36.3 to 11.3 °C, in dependence of increasing olein content). Fat content (from 5.3% to 30.7% on batter) and percentage of olein in the fat blend (from 42.7% to 92.2%) were varied. The increase of fat quantity enhanced cake softness, while lowering the volume; higher olein contents also decreased cake firmness. An optimised formulation containing 19.7% fat with 92% olein in the fat blend and showing good structural properties, comparable to those of a 18% butter reference cake, was identified. The optimised and the butter cake showed specific volume of 2.25 and 2.23 cm3 g−1, respectively, and load at 25% strain of 7.68 and 5.63 N. These results demonstrated the possibility to replace butter with a liquid vegetable fat blend, thus increasing unsaturated fat content and reducing total cholesterol in the product.