I use powdered butter in minute amounts in various recipes for trail food, get it from Packit Gourmet.
Olive Oil is easier, needs no reconstitution. .4 fl oz (about 1 tablespoon) has 120 calories. 14 grams of saturated fat.
The butter powder i get from Packit has 15 calories per 1/2 tsp serving, 10 from the single gram of saturated fat.
If you're trying to pack minimal bulk, with maximum calories, the winner is clear.