Keep the fresh spent grain refrigerated until you are ready to begin work with it.

Eliminate as much of the moisture content as possible by placing in a cheese cloth and squeezing out the water or placing spent grains in a colander over a baking sheet and pressing on it to squeeze out moisture. if you feel so inclined, a good old fist squeeze is really effective, just needs to be repeated quite a few times.

Spread the spent grain into thin layer onto as many baking sheets as your quantity needs. You may need to dry two batches of four baking sheets consecutively. Keep any spent grains not being dried in the refrigerator.

Dry in oven set to the lowest setting, usually this is 150°F, for 4 - 6 hours. Precise time depends on how much moisture you were able to squeeze out already and how thick you spread the grain onto the baking sheets.

Occasionally move the grains around with a wooden spoon to help them dry out more evenly.

When the grain is completely dry, take the sheets out of the oven and allow it to cool off.

Use a powerful blender or a grain mill attachment to grind the dried spent grain into a flour with a fine consistency. Work in small batches.

Store spent grain flour in an air tight container.