I use the highest cal foods i can find that don't require much quantity and try do it 7 times a day. If it's under 450 cals, it's not on my list.
Eg: add 1 tblsp macadamia oil and 1 of olive and you have 300 extra cals in your shake, add a spoon of lsa and there is another 80 odd.
Add olive oil...