We have tried multiple ways of giving breast milk at daycare, he used to take it fine but now will not.
I know you say you've tried various ways, have you tried a milk pudding? blancmange? You can literally just add corn flour and cook it through then let it set to make a firm pudding which can be eaten with a spoon. Add some flavour such as vanilla or nutmeg if you like or perhaps a whizzes/pureed banana for flavour. Or firm egg custard made with breast milk (so there are eggs as well as milk).
At this age I still looked at having a balanced diet over a week rather than each day/meal, it's possible he's taking enough during the time he is not in day care. You could also have more fats during the days he is not in day care such as nut butters (smooth). Mine certainly had some days which were more on the side of veg and some more on the side of proteins for instance but it all balanced across the week.
Seeds are high fat, not a great food in themselves for young LOs but tahini might be an option added to a sandwich or other home cooked foods.
Eggs? eggy bread, fritata, quiche, omelet, or used in baking. There's a chick pea cupcake recipe which is very eggy for instance.
