Place ¼ cup chia seeds, ¼ cup hemp seeds and ¼ cup pepitas in a spice grinder. Pulse just until finely ground, about 10 pulses. Transfer to a bowl.
Repeat in 3 more batches with the remaining chia seeds and hemp seeds. Stir to combine.
Alternatively, pulse all ingredients together in a high-speed blender until finely ground, about 15 (1-second) pulses, stopping to scrape the seed mixture from the bottom of the blender occasionally.
