I need a quick help... I'm planning to decorate a 11x15 inch shet ake for my daughter's 2nd B'day... So for between the layers can I make a raspberry filling like this...

I put about 20 oz frozen rasp. in a glass bowl, added 1/2 cup sugar & 2 TSB water.. Then kept on high for about 8-10 mins & crushed the rasp. My Q is after this can I add 1 cup of butter cream icing into it just to get the thick filling & to cancel the tanginess of raspberry? I'm on hold till this step... PLEASE HELP

It will add sweetness, but I don't think it will thicken the filling.

If you need it to be thicker, you can cook it with a thickener like arrowroot or cornstarch. Once it is thicker, then add icing.

Just my opinion