Inductor core including: a base core portion having a first surface and an opposite second surface; an inner core portion extending from the first surface in a direction transverse to the first surface; an outer core portion extending, in the direction transverse to the first surface, from the first surface to an end surface of the outer core portion, the outer core portion at least partly surrounding the inner core portion, thereby forming a space around the inner core portion for accommodating a winding; wherein the first surface includes a recess for accommodating a connection portion of the winding, said recess extending at least a part of a distance between the inner core portion and the outer core portion, and wherein the outer core portion presents a slit extending from said end surface towards the recess, and wherein the second surface comprises a first protrusion oppositely arranged to the recess.