Effective communication in English, especially in writing, holds increasing global significance. Despite exposure to all four language skills, ESL learners often find writing most challenging. This sentiment is echoed within English education system and ESL learners in Malaysia, which highlight the importance of writing while acknowledging its difficulty to master. This research addresses the relatively unexplored area of expository writing challenges among ESL learners, which aims to enhance their proficiency in this writing genre by exploring into ESL teachers' perspectives on the challenges ESL learners encounter in writing expository essays. Utilising Sidek's Module Development Framework, 8 English teachers, each with over 5 years of teaching experience across secondary levels, participated in this needs analysis interview. The findings revealed several key challenges, where ESL learners displayed limited knowledge and understanding of topics, struggled with maintaining flow and coherence in their expositions, exhibited limited vocabulary and grammar proficiency and the teachers encountered difficulty aligning writing topics with students' interest. To address these hurdles and enhance writing skills, integrating more interactive and student-centered learning strategies into ESL writing lessons is recommended. Ultimately, these findings serve as the groundwork for developing a tailored writing module to improve ESL teachers' and learners' expository writing proficiency.