Prep the pan and oven: Heat the oven to 350°F (175°C). Grease a 9-inch round cake pan or an 8-inch square pan.
Line the bottom with parchment if you want easy unmolding.
Blend the wet ingredients: In a blender, add condensed milk, coconut milk, whole milk, eggs, melted butter, vanilla, and salt. Blend until smooth and well combined, about 20–30 seconds.
Add dry ingredients: Add the flour and sugar (if using). Blend again just until smooth.
Avoid over-blending once the flour goes in.
Fold in coconut: Stir in the shredded coconut by hand so it stays textured throughout the cake.
Pour and smooth: Transfer the batter to the prepared pan. Tap gently to release air bubbles. Sprinkle a tiny pinch of cinnamon or nutmeg on top if you like.
Bake: Bake for 35–45 minutes, until the edges are set, the top is lightly golden, and the center has a slight jiggle but isn’t liquid.
A toothpick near the edge should come out mostly clean.
Cool: Let it cool in the pan for 20–30 minutes. It will firm up as it rests. Serve warm for a softer custard texture, or chill for cleaner slices.
Slice and serve: Run a knife around the edges, slice, and plate.
Add a light dusting of coconut or a spoon of lightly whipped cream if you want something extra.