The night before in a large bowl, mix oats, gluten free starter, flour, and non-dairy milk together. Cover with a towel and let sit overnight on the counter. Let sit for at least 7-8 hours.
The next day, in a separate bowl, melt butter, add in olive oil, maple syrup, and eggs. Whisk to combine.
Sprinkle cream of tarter, baking soda, and cinnamon on top of flour and oat mixture. Use hand mixer or stand mixer to combine, then slowly pour in egg/oil mixture until well combined.
After waffle iron is pre-heated, scoop 1/3 to 1/2 a cup onto waffle iron and cook according to manufacturer's directions.
Optional top with fruit, more maple syrup, butter, or homemade fruit sauce. We love just combining some frozen blueberries or strawberries in a pan with some maple syrup and letting simmer until thick.