In Focus Best Kept Secret PHIL JACOBS Editor 0 kay, so you've heard the cliche, "Best Kept Secret" before. This time, we really have one for you. Only, judging from the line that forms at about 10:30 Thursday nights, the word is getting out. That's when people from all over the community come to buy fresh . challahs for Shabbat. Sometimes the challahs are so fresh, customers wait a few moments for the cake-like bread to cool. And the smells. Short of the Sabbath itself, nothing can lift one's soul higher than the warm, wonderful aroma of baked challah. 9/26 1997 86 4001101. i.,0111111.0011101, Kerry Silver, manager of Bagels Plus on Lincoln, at Greenfield, start- ed offering the challahs last Rosh Hashanah. "It sort of was the best kept secret," said Silver. "Even people liv- ing around the corner from us didn't know." The store has now quadrupled the number of challahs it makes for Shabbat: some 750 challahs per week. "The number one thing we hear is that's not a bakery-style challah. There's a bakery-style challah and a home-style challah. People literally stop us on the street, telling us they're fantastic, they're great. "For us, the best part is that this is something we enjoy. It's a labor of love."