1. Line a 9 x 5-inch loaf pan with heavy-duty foil. Place meringue cookies in a large plastic bag. With back of measuring cup, gently tap meringue cookies to crush slightly.
2. Layer 1 cup meringue crumbs in bottom of prepared pan. In medium-size bowl, combine 1 cup of the heavy cream, 2 tablespoons of the sugar and instant espresso powder. With electric mixer, beat until soft peaks form. Evenly spread cream mixture in pan. Top with 1 cup meringue crumbs; slightly pat into mixture.
3. In same bowl, combine mousse mix and milk. Prepare as package label directs. Evenly spread in prepared pan. Top with remaining meringue crumbs, slightly pressing into mousse. Cover with plastic wrap; freeze 3 hours or overnight.
4. To serve, beat remaining 1/2 cup heavy cream with 1 tablespoon sugar until soft peaks form. Remove plastic wrap from marjolaine. Place serving platter on top. Invert; carefully peel away foil. Spread whipped cream over top; sprinkle with cocoa powder, if desired.