We removed the seeds from our raspberries before incorporating the puree into the batter. To do this, we blended them in a food processor before pressing the the puree with the back of a spoon through a metal mesh sifter or sieve. Some of our fruity cake recipes (like our scratch Raspberry Cake) call for heating the puree in a saucepan on the stovetop to concentrate the flavor and reduce the amount liquid. However, we did not make a reduction for today's cake.