Homemade baby food with breast milk

I plan on making my own baby food in the beginning (when baby is 6 months). I wanna make purees with breastmilk and freeze it. The main reason I want to do this is so I can make small 1 ounce portions (instead of the typical 2.5 oz containers in store).  I know baby won't eat a lot in the beginning. Not interested in "baby led weaning" so no need for those comments. 
Is it okay to make the purée, add fresh pumped milk, and then freeze it mixed together? 
Or are you suppose to make purée and freeze it separately from breastmilk. And when it's time to eat it, thaw separated milk and purée THEN mix together?