Line a 13-by-9-inch pan with parchment paper and set aside. In a large bowl combine the millet, flax seeds, oats, coconut, hemp, chia and maca if using.
Roughly chop the dates and add to a food processor with the almond butter, cacao, coconut oil, brown rice syrup, 4 teaspoons water, the vanilla extract and salt, and blend until combined. Add to the dry mix and mix until completely combined. Press evenly into the prepared tray and freeze until completely cold and firm, 2 hours.
Remove and slice into 24 1-by-2-inch bars. Store in an airtight container in the freezer for up to 3 months.