SAUCE: Puree raspberries and syrup in processor. Strain. Chill
CAKE: Preheat oven to 350°. Line bottom of 9" cake pan with 2"-high sides with parchment or wax paper.
Place all chocolate in large bowl. In medium saucepan, bring butter, espresso and sugar to boil, stirring to dissolve sugar. Add to chocolate; whisk until smooth. Cool slightly. Whisk in eggs. Pour batter into prepared pan.
Place cake pan in a roasting pan. Pour enough hot water into roasting pan to come halfway up sides of cake pan. Bake until center of cake is set and toothpick inserted into center comes out with a few moist crumbs attached, about 1 hour. Remove pan from water. Chill cake overnight.
Cut around pan sides to loosen cake. Using oven mitts as aid, hold pan bottom over low heat for 15 seconds, warming slightly to release cake. Place platter over pan. Hold pan and platter together tightly and invert. Lift off cake pan; peel off parchment.
Serve with sauce and fresh berries.