Yes, you do need a candy thermometer for this homemade chocolate sponge candy. Preferably, u003cstrongu003eselect a u003ca href=u0022https://amzn.to/3mVUdgLu0022 target=u0022_blanku0022 rel=u0022noreferrer noopener nofollowu0022u003ethermometer with a pot clipu003c/au003e. u003c/strongu003eYou're going to be boiling sugar and water to 300F degrees, exactly, and there is simply no way to guess.