The newest development in fine dining is the co-chef -- two executive chefs who collaborate on everything from recipe and menu development to purveyor contacts to kitchen duties. And with the addition of Todd Zimmer, former top toque at Mark's in the Park (Boca Raton) and Café Maxx (Pompano Beach), Lake Avenue Grill (in the GulfStream Hotel, 1 Lake Ave., Lake Worth, 561-227-7230) has swung onto the trendwagon. Zimmer joins existing exec Anthony Hruska, who cut his culinary teeth at Norman's (Coral Gables). Between the two of them, they have experienced the guidance of three of South Florida's celebrity chefs -- Mark Militello, Oliver Saucy, and Norman Van Aken. Based on that gastronomic pedigree alone, it just might appear that the Lake is about to become a significant destination that's Worth-y indeed, if only for name-dropping.