1/4 cup plus 1 tablespoon OLD MILL Plain Flour
3 tablespoons unsweetened cocoa powder
1/8 teaspoon salt
3 large eggs, at room temperature
1/2 cup sugar
2 teaspoons very hot tap water
2 1/2 tablespoons unsalted butter, melted
1/4 cup plus 2 tablespoons OLD MILL Raspberry Jelly, warmed, divided
4 ounces bittersweet or semisweet chocolate, finely chopped and divided
3/4 cup heavy (whipping) cream
Preheat oven to 400 degrees F. Lightly coat an 8-inch square baking pan with cooking spray; line bottom of pan with a strip of parchment paper, allowing it to come up sides of pan with 1 inch overhang. Coat paper with cooking spray.
Sift flour, cocoa, and salt into a small bowl. Place eggs, sugar, and tap water in a small, deep mixing bowl; beat with a handheld electric mixer until thick and a heavy ribbon falls back into bowl when beaters are lifted, about 4 minutes. Sift dry ingredients, in two batches, over egg mixture; fold in gently. Fold in melted butter. Do not overmix or batter will deflate. Spread into prepared pan.
Bake until a toothpick inserted in center comes out clean, 11 to 12 minutes. Let cake cool in pan on wire rack for 10 minutes. Use paper to lift cake from pan and cool completely on wire rack.
Carefully invert cake onto a cutting board lined with parchment paper. Using a 3 1/2-inch, heart-shaped cutter, cut out four cakes. Reserve scraps for nibbling. Gently brush tops and sides of heart cakes with 3 tablespoons jelly.
For filling, microwave 2 ounces chocolate in a small microwave-safe bowl on medium power until soft, about 1 1/2 minutes. Stir until smooth; stir in 1 tablespoon jelly. While chocolate mixture is warm, beat 1/2 cup of the whipping cream in a small, deep mixing bowl until stiff peaks form; quickly beat in the chocolate until smooth. Spoon mousse over two of the heart cakes, spreading almost to edges. Place remaining heart cakes, jelly-sides-down, on mousse layers and press gently to adhere. Smooth side of cake with a table knife, smoothing sides. Refrigerate while preparing glaze.
For glaze, bring remaining 1/4 cup cream and 2 tablespoons jelly to a boil in a small saucepan or microwave-safe bowl. Remove from heat and stir in remaining 2 ounces chopped chocolate. Let cool until thickened but slightly pourable, about 15 to 20 minutes. Pour and spread glaze to cover cakes. Chill until firm, 2 hours or overnight. Makes 2 cakes.