In a large bowl, whisk together coconut milk, spiced rum, eggs, nutmeg, cinnamon, and vanilla until well combined.
Spray a large skillet or griddle with cooking spray. Soak each slice of the bread in coconut milk-egg mixture and place on a hot skillet, 1-2 slices at a time. Cook on medium-high heat on both sides until golden, about 2-3 minutes.
Transfer to a plate and top the french toast with toasted coconut flakes, powdered sugar, cinnamon, and/or maple syrup. Serve immediately. Enjoy!