Step 1: Cook the oats. Bring water, milk, or plant-based milk to a boil in a small saucepan. Stir in the rolled oats or steel-cut oats and cook according to package directions until soft and most liquid is absorbed, about 5-7 minutes for rolled oats (longer for steel-cut). If desired, lightly toast the dry oats in the pan for 1-2 minutes before adding liquid for extra flavor.
Step 2: Stir in cheese (optional). Once the oats are cooked and removed from heat, stir in Parmesan or goat cheese (if using) until melted and creamy. Season with a pinch of salt and pepper to taste.
Step 3: Poach the egg. While the oats are cooking, heat a separate small pot of water to a gentle simmer (not a rolling boil). Create a gentle whirlpool in the simmering water with a spoon, then carefully crack an egg into the center. Cook for approximately 3 minutes for a runny yolk, or longer for a firmer yolk. Gently scoop out the poached egg with a slotted spoon.
Step 4: Assemble. Pour the cooked savory oatmeal into a bowl. Carefully place the poached egg on top of the oatmeal.
Step 5: Add toppings and serve. Garnish with your favorite toppings such as roasted almonds, sautéed spinach or mushrooms, fresh chives, a dash of black pepper, or a sprinkle of red pepper flakes. Enjoy immediately while warm.