Created by ellie on April 2, 2017
Step 1: In as saucepan over medium heat bring the raspberries, sugar, lemon zest and juice to a boil. Reduce heat to medium low and simmer for 5 minutes. Transfer to blender and process until smooth. Strain mixture through a fine mesh sieve; discard solids. Return mixture to saucepan and heat over medium heat.
Step 2: In a medium bowl whisk together the egg yolks, cornstarch and salt. Add about 1/4 cup hot raspberry mixture to eggs, whisking constantly. Add egg mixture to hot raspberry mixture (in saucepan) and cook over medium high heat until thickened 5-10 minutes. Remove from heat and add butter, 1 tablespoon at a time, whisking to combine after each addition.
Step 3: Let cool completely in refrigerator before using -- at least 2 hours.
Step 4: May be stored in refrigerator for up to one week.