Add the oats, milk (or water), cinnamon and honey (if using), and salt to a microwave-safe bowl. Cook for 90 seconds to 2 minutes, stopping to stir the oatmeal halfway through cooking to prevent it from bubbling over.
When the oats are soft and ready to serve, add the Greek yogurt and stir to incorporate it into the oatmeal.
Stovetop:
Add the oats, milk (or water), cinnamon and honey (if using), and salt in a small saucepan over medium-high heat. Use the smallest saucepan you have, or double the recipe and save leftovers. Bring the mixture to a simmer, stirring occasionally, and once it simmers, reduce the heat to low.
Cook for 5 minutes, stirring from time to time, until the desired consistency is reached. When the oats are soft and ready, turn off the heat and add the Greek yogurt. Stir to incorporate and heat it through.
Serve:
Serve the oats in a bowl, topped with your favorite oatmeal toppings.
Notes
Using milk will yield a creamier oatmeal.
Using instant/quick oats reduces the cooking time to about 2 minutes on the stove and 1 minute in the microwave.
Any flavor Greek yogurt can be used, with vanilla being the most universal for toppings.