Hold your horses, Frank Pepe fans: The New Haven-style pizzeria needs a little extra time in the oven. Originally scheduled to open March 21st at Westfield Montgomery mall, Frank Pepe is now planning a March 28th opening in the old Bobby’s Burger space across from Cheesecake Factory. The family-owned chain, which dates back almost 100 years, is known for its coal-fired thin crusts and signature white clam pizzas.