Behind every number is a real person who cares. Our team combines deep nonprofit accounting expertise with a genuine commitment to supporting the leaders doing mission-driven work.

Rosemary Siens, EA
Owner & Founder

Rosemary is Mosaic’s Founder and CEO, serving as the firm’s lead nonprofit accounting expert. She is an Enrolled Agent (EA) and QuickBooks Online Advanced ProAdvisor, with a Master’s in Accounting from Ohio University and undergraduate degrees in Environmental Policy and Latin American Studies from Prescott College. Rosemary founded Mosaic Bookkeeping in 2018 to support nonprofits by building strong accounting systems and best-in-class financial practices. Outside of work, she enjoys surfing, roller skating, canoeing, and salsa dancing.

Amanda Bell
Accounts Payable & Payroll

Amanda is Mosaic’s Accounts Payable and Payroll Specialist, ensuring accurate processing and strong internal controls for clients. With over 20 years of experience in customer service, data entry, and quality control, she brings a detail-oriented, analytical approach to her work. Amanda is QuickBooks Online certified and supports nonprofits by providing consistent separation of duties that reduces risk. Outside of work, she enjoys exploring nature, playing board games with her family, creating fiber arts and stained glass, volunteering with local nonprofits, and planning events with friends.

Alyssa Huffman
Lead Accounts Specialist

Alyssa is Mosaic’s Lead Accounts Manager, overseeing our bookkeeping team and ensuring consistent, high-quality client service. She is QuickBooks certified and known for her motivation, attention to detail, thoughtful leadership and passion for education. Outside of work, she enjoys organizing gatherings, hosting friends, and bringing people together—reflecting the same care and heart she brings to her work every day.

Jordan Miller
Bookkeeping Specialist

Jordan is Mosaic’s Bookkeeping Specialist, known for her attention to detail and tech-savvy approach to client support. She is QuickBooks certified and brings a background in IT, which helps her navigate accounting systems efficiently and accurately. Since joining Mosaic in 2023, Jordan has supported clients with bookkeeping, Form 990 data entry, and administrative tasks, while working toward her IRS AFSP certification. Outside of work, she enjoys board games, video games, and spending time with her ever-helpful office-assistant cats.

Shuli Zerin
Bookkeeping Specialist

Shuli is a Bookkeeping Specialist at Mosaic and a QuickBooks ProAdvisor, bringing a rare blend of academic rigor, entrepreneurial experience, and nonprofit leadership to her work. She holds a PhD and previously ran her own business as a Yiddish teacher, as well as helping establish a nonprofit dedicated to empowering female composers. With a deep commitment to education, Shuli approaches her work with a heart for teaching and empowering clients to better understand their finances. Outside of work, she enjoys playing music, cooking, learning, teaching, and building community.

Eric Siens
Onboarding Specialist/Lead Accounts Manager

Eric is Mosaic’s Lead Accounts Manager and Onboarding Specialist, supporting clients and the team through thoughtful systems design and process improvement. QuickBooks-certified and Excel expert, Eric builds efficient workflows that set clients up for long-term success. Eric holds a bachelor’s degree from Ohio University and brings 10 years of accounting experience. Outside of work, he enjoys board games, and is a master chef on the grill

Sara Litsey
Bookkeeping Specialist

Sara is a Bookkeeping Specialist at Mosaic, known for her strong communication skills and thoughtful, detail-oriented approach to client support. She is QuickBooks certified and is currently working toward her bachelor’s degree in accounting. With a background in the healthcare and wellness industries, Sara brings both technical expertise and a genuine heart for supporting nonprofit organizations. Outside of work, she enjoys spending time with her family, focusing on health and wellness, and doting on her cats.