I had a free frozen drink on my Panera Rewards Card last week & got my son a berry smoothie with it. I read the ingredients on the berry syrup they use & it was natural enough. Just berries & sugar mostly. Then, I watched how she made it so I could copy it at home. I'm glad I did because that was a really good smoothie!
I buy these big bags of organic mixed berries frozen from BJs. They have strawberries, blackberries, raspberries & blueberries. So, I thawed them and pureed them in my food processor, then strained them through a fine mesh strainer. You really have to take a couple minutes for this. Use a spatula & push it around. The goal is to get the berry puree into a bowl beneath & capture most of the seeds in your strainer. I've used this berry mix to make the kids smoothies before & they were a little crunchy because of all the seeds. That was not their favorite.
Now I have a tall jar of mixed berry puree in the fridge.
Here is my copycat version of a Panera Berry Smoothie...
Add to blender-
1 cup ice
2 ice cream scoops of your favorite vanilla yogurt
(they use Stonyfield Farms at Panera, I saw her scoop it)
maybe 1/4 cup of berry puree (I just poured a little in until it looked right)
Blend until it is smooth & creamy. Taste it & add sugar if you think it needs it.