Weigh or lightly spoon flour into dry measuring cups; level with a knife. Sift together flour, cocoa, espresso powder, baking powder and salt.
Place butter in a large bowl; beat with a mixer at medium 1 minute. Add sugar and brown sugar, beating until well blended (about 5 minutes). Add egg substitute and vanilla, beating until well blended. Fold flour mixture into sugar mixture; fold in chocolate. Divide batter evenly among 10 (4 once) ramekins; arrange ramakins on a pan. Cover and refridgerate 4 hours or up to 2 days.
Preheat oven to 350 F
Let ramakins stand at room temperature 10 minutes. Uncover and bake at 350 F for 21 minutes or until cakes are puffy and slightly crusty on top. Sprinkle evenly with powdered sugar; serve immediately.