I found that a heaping 1/2 cup of oat groats will give you 1 cup of oats.
2 cups Water (you can use milk or a mixture of milk & water)
Dash of Salt
Add your water and oats to a saucepan and cook on medium-high heat. Give it a stir every now and then and cook until they reach your desired consistency. Add in sweeteners, fruit, nuts, etc. and enjoy. We enjoy adding butter, coconut sugar, and maple syrup.