A mixing paddle that is configured to rotate about a horizontal rotation axis and includes at least one eccentric arm which includes a first portion inclined with respect to a plane containing the rotation axis, so as to cause the ingredients contained in the mixing chamber to move in a first axial direction when the mixing paddle rotates in a first direction of rotation, a second portion having a cross section oriented radially with respect to the rotation axis in order, when the mixing paddle rotates in a second direction of rotation, to bring about a radial movement of the ingredients towards the outside of the mixing chamber.