Assemblies and inserts are provided for evenly heating a smokable substance. A hookah bowl insert is provided for heating a smokable substance. The insert has a central core having at least one passageway extending therethrough. The insert further has a plurality of radial extensions extending in a radial direction from the central core. The radial extensions may be for gripping the smokable substance therebetween, and each radial extension has a vertical extension extending in a direction perpendicular to the radial direction. The insert is formed from a heat conductive material, such that heat is distributed across the insert, and within the individual radial and vertical extensions. Each vertical extension has a thickness larger than a thickness of the insert at the central core. As such, the vertical extensions can maintain stable temperatures and transfer heat to and from the smokable substance located therebetween.