Can a Light Domain Cleric cast Burning Hands while carrying a shield?

I have a Light Domain Cleric who gets, as part of the Light Domain, the Burning Hands spell. Can I cast this spell while carrying a shield?

I subscribe to the idea that one physically must touch one’s thumbs together and spread one’s fingers per the spell as the somatic component of the spell. Is it reasonable to think that a Cleric with a shield strapped to their arm is able to make such a gesture and not burn their own shield?