Rinse the oats under cold running water in a fine-mesh sieve, then set aside.

Combine the rinsed oats, water (or milk), brown sugar, salt, cinnamon, and nutmeg in a medium saucepan over medium heat.

Increase heat to medium-high and bring the mixture to a gentle boil.

Reduce heat to low and let simmer for 5-7 minutes, stirring occasionally.

Remove from heat and stir in the espresso and butter until fully melted and incorporated.

Spoon the oatmeal into serving bowls while warm.

Drizzle milk or cream over the top if desired.

Garnish with your choice of toppings and enjoy!