A method and system for making a low-water activity filling, such as crème type fillings, is provided. The fillings advantageously can be used with rotary sandwiching machines without the need for a cooling tunnel downstream of the scraped-surface heat exchanger in the production line. The fillings produced herein comprise a fat component and sugar source, and the fat in the filling has the desired crystalinity. The process and system described herein unexpectedly achieve both a desired nucleation and crystallization rate and crystal structure, as well as the resulting increased filling firmness, in the fillings produced therewith.