Heat a medium skillet over a medium-low heat and add mixture. Spread it evenly throughout the pan.
Continue to stir and move the oats to prevent burning but keep a shallow, even layer in order to crisp the oats. Add more butter if necessary, to keep the oats moist until browned.
Once browned, spread the oats in a thin layer on a cookie sheet to cool and finish crisping.
In the same pan, now heat your blueberry pie filling.