In a saucepan combine raspberries and sugar. Cook on medium heat for about 10 minutes, stirring frequently to prevent burning.
Take off the heat and run a spatula through the sauce, if it spits but still comes together it's ready. Keep in mind that as it cools it will thicken even more.
Pour the sauce through a sieve over a bowl. Stir the sauce till only the raspberry seeds are left. Scrap the bottom of the sieve. If there are still seeds in the sauce you may pass it through the sieve one more time.
Transfer the raspberry sauce to a jar, or use as needed.