Seedless Raspberry Cake Filling

This is my absolute favorite raspberry filling. Actually, probably my favorite filling in general. Any time that someone has this filling, they are constantly talking about how amazing it is. I use it both in cupcakes and between cake layers. And if you are lucky enough to have a little leftover, it is great on pancakes, ice cream, or plain and eaten with a spoon.

Ingredients
12 oz frozen unsweetened raspberries, thawed
1/2 cup sugar
1 tsp lemon juice
2 heaping tablespoons cornstarch

Directions
1. Thaw raspberries.
2. With a fine wire strainer, use a spoon to press the raspberries so that the seedless pulp falls into a bowl below.  Strain enough pulp to get between 1/3 - 1/2 cup of pulp (I usually get close to the 3/4 cup). (You can skip this step and just use the whole berries, but people at weddings and parties don't like to pick seeds out of their teeth). Add enough water to equal 3/4 cups.
3. In a small saucepan, combine raspberry juice/water, sugar, lemon juice, and cornstarch.  Cook over medium heat, whisking constantly, until mixture bubbles and thickens (remember it will continue to thicken as it cools).  Remove from heat, set aside.
4. Cool and place in the refrigerator for up to a week.