Making grain spawn with excess corn

I have excess corn that I want to use to grow mushrooms. I've never grown mushrooms before but I have been studying the process. I think I understand the basics but will use this as my first trial.

So here's my question. I've ordered a block of grain spawn and I have this excess of corn. I can break up that original block and colonize all my corn--in multiple batches--right? For instance, can I make a bag layering pasteurized corn with grain spore, then after the mycelium takes it over I can break it up and then use that to make more blocks?

Perhaps but if you only pasteurize not sterilize the medium I would start fruiting.
Multiplication needs to happen sterile or a high percentage will spoil with mold and bacteria.

You can't keep the grain spawn for long to do multiple batches as every opening brings the risk of contamination.
Storage time in the fridge is also not indefinite.

Work in one batch but put the first portions into sterilized mason chars with grain - use the new grain spawn to do the next batches.
Do the transfers in a still air box.