Here is how to make the Cooked Strawberry Puree. Use 1/3 cup of chopped strawberries and blend in a blender on high until smooth. If you want to remove the seeds, then pour through a fine mesh sieve. Next, cook and reduce the strawberry puree by putting it in a small sauce pan over medium-high heat and then bring it to a simmer while stirring. Once at a simmer, reduce the heat to low and stir frequently until desired thickness is reached, up to 20 minutes. Stir frequently so that it doesn't stick to the bottom of your pan. Let cool. Use in this recipe and then for any remainder, refrigerate for up to 2 days or freeze for up to 6 months.