“Cheesecake’s great. Fifteens are great, I thought: ‘What would happen if I put them together?’” With characteristic succinctness, Jonny Murphy — aka social media baker The Hungry Hooker — is describing the thought process behind his Fifteens Cheesecake, a recipe based on the traditional, desiccated coconut-dusted Northern Irish traybake that’s now been viewed more than 1.3 million times on his Instagram page.