Heat most of the milk together with the sugar in a pot, without boiling.

Mash the cornstarch with the remaining cold milk until lump-free, then add to the hot milk; add the almond flour as well, and cook over low heat, stirring constantly, until thickened.

Add the vanilla and stir, then divide the mixture among serving bowls.

Once the bowls reach room temperature, chill in the refrigerator for at least one hour; garnish with roasted sliced almonds before serving.