Add the rolled oats, quick oats, flax seed, and walnuts to a bowl and mix to combine.
Pour in the rest of the ingredients: coconut oil, sourdough discard, chopped dates, and oatmilk. Mix until all of the ingredients are incorporated and the chopped dates are distributed throughout the mixture.
Spread the granola mixture on a baking sheet with parchment paper. Bake at 350° for about 15 minutes or until the granola begins to turn golden brown. If you like crunchier granola, mix the granola and bake for an additional 5 minutes. Enjoy!