In a microwave or in a large saucepan over low heat, melt marshmallows and oil; stir until smooth. Remove from heat; stir in extract. Stir in cereal and 1/2 cup of espresso beans. Press mixture into a lightly-greased 13x9-in. baking pan using wax paper or a lightly-greased spatula. Cool to room temperature. Spread melted chocolate on top and sprinkle with remaining 1/2 cup of espresso beans. Cut into bars.