A method for forming a decorative layer (GL) on a surface (S) of a food product (PB), in particular a cap of icing on a convex top surface of the said food product, includes the steps of simultaneously depositing a plurality of metered quantities in the form of drops (GC) of a decorating material (C) on this surface (S) so that they are spaced from each other thereon, and of causing the said metered quantities or drops (GC) to spread so as to form the decorative layer (GL) by means of a blowing or vibrating action. The invention also comprehends a decorating machine for forming a decorative layer (GL) on a surface (S) of a food product (PB), in particular a cap of icing deposited on a convex top surface of this food product, including dispenser devices (8, 16, 21) for simultaneously depositing a plurality of metered quantities in the form of drops (GC) of a decorating material (C) in a fluid state on the surface (S) in portions spaced from each other thereon, and blower (51) or vibrator (53) means for causing the metered quantities or drops (GC) to spread and form the decorative layer (GL).