Preheat the oven to 375°F (190°C). Lightly grease an 8×8-inch square baking dish.
Place the oats in a large mixing bowl. Add the coffee, almond milk, maple syrup, nut butter, melted coconut oil, ground flaxseed, baking powder, vanilla extract, and sea salt.
Stir everything together until the mixture is fully combined.
Pour the mixture into the prepared baking dish and spread it out evenly.
Bake for 35 to 40 minutes, or until the center is set and a toothpick inserted in the middle comes out clean.
Allow it to cool for about 10 to 15 minutes. Slice into 6 portions and serve warm with extra nut butter or maple syrup if desired.