Beat first 4 ingredients at medium speed with an electric mixer until blended.
Combine flour and next 6 ingredients; add to molasses mixture alternately with hot water, beginning and ending with flour mixture. Beat at low speed after each addition. Pour batter into prepared pan.
Bake at 350° for 32 to 35 minutes or until a long wooden pick inserted in center comes out clean. Cool cake in pan on a wire rack 15 minutes.
Meanwhile, combine 1/2 cup sugar, 2/3 cup water, lemon juice, and lemon extract in a small saucepan; simmer over medium-low heat 5 minutes, stirring to dissolve sugar. Remove from heat, and let cool 10 minutes.
Poke holes in top of cake using a skewer. Pour syrup over cake. Cool completely. Invert cake onto a serving platter; lightly sprinkle with powdered sugar. Garnish, if desired.