Prep the mango: Peel and dice the mango into bite-size pieces. Set aside.
If your mango is very soft, save some to mash into the oats for extra sweetness.
Toast the coconut flakes: In a dry skillet over medium heat, toast coconut flakes for 2–3 minutes, stirring, until golden and fragrant. Remove and cool.
Stovetop method: In a small pot, add rolled oats, coconut milk, water, vanilla, salt, and cardamom or cinnamon. Bring to a gentle simmer over medium heat, stirring.
Cook to creamy: Reduce heat to low and cook 5–7 minutes, stirring occasionally, until thickened.
Add more water if needed. Stir in honey or maple to taste.
Fold in mango: Add half the mango to the pot and stir gently to warm it through. Reserve the rest for topping.
Serve: Spoon oats into bowls.
Top with remaining mango, toasted coconut flakes, and any optional add-ins like a dollop of yogurt or a sprinkle of chia.
Overnight oats method: In a jar, combine oats, coconut milk, 1/2 cup water, vanilla, salt, sweetener, and chia if using. Stir well. Fold in half the mango.
Cover and chill overnight (or at least 4 hours). In the morning, stir, add more liquid if needed, and top with remaining mango and toasted coconut.