Heat oven to 325°F. Grease and flour 9x5-inch loaf pan; set aside.
Combine flour, cinnamon, ginger, baking powder and salt in bowl. Set aside.
Beat butter and brown sugar in bowl at medium speed, scraping bowl often, until light and fluffy. Add 1 egg at a time, beating well after each addition. Add molasses; continue beating, scraping bowl often, until well mixed. Add flour mixture; beat at low speed until just moistened.
Spoon batter into prepared pan. Sprinkle top with raw sugar. Bake 55-65 minutes or until toothpick inserted in center comes out clean. Cool 15 minutes; remove from pan. Cool completely.
Combine sugar, cornstarch and grated lemon zest in small saucepan. Gradually stir in water. Cook over medium heat, stirring constantly, 4-5 minutes or until mixture comes to a full boil. Boil for 1 minute. Gradually stir half of hot mixture into beaten egg yolks with whisk. Return all mixture to saucepan. Continue cooking, stirring constantly, 2 minutes or until mixture reaches 160°F. and is thickened. Whisk in lemon juice. Cool slightly. Cover surface with plastic food wrap. Refrigerate 1 hour or until completely cooled.
Beat whipping cream in bowl at high speed until soft peaks form. Fold into lemon mixture. Cut cake into 20 thin slices.
Place 2 cake slices onto individual serving plate; spoon lemon topping over cake. Lightly sprinkle with cinnamon. Garnish with lemon twist, if desired.