Cake:
4 tablespoons unsalted butter, melted

1/3 cup all purpose flour
1/3 cup unsweetened cocoa powder
1/4 teaspoon salt
4 large eggs
3/4 cup sugar

Mousse Base:
1 cup heavy whipping cream
4 cinnamon sticks, broken in half

Mousse, Cake Assembly, and Glaze:
2/3 cup cherry jam
2 tablespoons kirsch (clear cherry brandy)

4 ounces bittersweet (not unsweetened) or semisweet chocolate, finely chopped

1/2 cup heavy whipping cream
1/4 cup water
2 tablespoons light corn syrup
1 teaspoon chai-spiced tea leaves or Lapsang souchong smoked black tea leaves (from 1 tea bag)
5 ounces bittersweet (not unsweetened) or semisweet chocolate, coarsely chopped

Buy Chocolate

For Cake:
Preheat oven to 400 F. Place 8x2-inch heart-shaped cake ring on sheet of foil. Wrap foil up sides of ring. Brush foil and inside of ring with 1 tablespoon butter; dust with flour. Place on baking sheet. You could also use a buttered and floured 8-inch round cake pan with 2-inch-high sides.

Sift flour, cocoa, and salt into medium bowl. Combine eggs and sugar in large metal bowl. Set bowl over saucepan of simmering water (do not allow bottom of bowl to touch water). Whisk until sugar dissolves, about 2 minutes. Remove from over water. Using electric mixer, beat mixture until thick and billowy and heavy ribbon falls when beaters are lifted, about 5 minutes. Sift half of dry ingredients over; fold in gently. Repeat with remaining dry ingredients. Transfer 1/4 cup batter to small bowl; fold in 3 tablespoons butter. Gently fold butter mixture into batter; do not overmix or batter will deflate. Transfer batter to ring.

Bake cake until tester inserted into center comes out clean, about 20 minutes. Transfer cake with foil to rack; cool completely. (Can be made 1 day ahead. Cover and store at room temperature.)

For Mousse Base:
Bring whipping cream and cinnamon sticks just to simmer in heavy medium saucepan. Remove from heat; let steep 1 hour at room temperature. Cover and refrigerate cinnamon cream overnight.

For Mousse, Cake Assembly, and Glaze:
Blend jam and kirsch in small bowl. Cut around sides of cake; lift off ring. Using metal spatula, loosen cake from foil and transfer to rack. Using serrated knife, cut cake horizontally in half. Using tart pan bottom, transfer top cake layer to work surface; turn cut side up. Spread half of jam on cut side of both cake layers.

Strain cinnamon cream into large bowl; beat until soft peaks form. Stir finely chopped chocolate in heavy small saucepan over low heat until smooth. Quickly fold warm chocolate into whipped cream (chocolate must be warm to blend smoothly). Immediately drop mousse by dollops over bottom cake layer; spread to within 3/4 inch of edge. Gently press second layer, jam side down, atop mousse. Smooth sides of cake with offset spatula. Chill assembled cake on rack while preparing glaze.

Bring cream, 1/4 cup water, corn syrup, and tea to boil in small saucepan, stirring constantly. Remove from heat; steep 5 minutes. Strain into another small saucepan; return to boil.

Remove from heat. Add coarsely chopped chocolate; whisk until smooth. Cool glaze until thickened, but still pourable, about 30 minutes. Place rack with cake over baking sheet. Slowly pour glaze over cake to cover, using spatula if necessary to spread evenly. Chill until glaze is firm, at least 2 hours and up to 1 day. Place cake on platter and serve.