Heat oven to 375ºF. Line bottom of 13×9-inch baking pan with parchment paper; set aside.
Combine flour, cocoa, baking powder and salt in bowl. Set aside.
Combine 3/4 cup sugar, eggs and 1 teaspoon vanilla in another bowl; beat at high speed 5 minutes or until fluffy, thick and pale yellow color. Stir melted butter into egg mixture; gently stir flour mixture into egg mixture until just combined. Spread into prepared pan.
Bake 11-13 minutes or until center springs back when touched. Run knife around edges to loosen sides. Let cool.
Combine 1/4 cup sugar, cream cheese and 1/2 teaspoon vanilla in bowl; beat until creamy. Add 1/2 cup whipping cream; continue beating until soft peaks form. Place 1/2 cup whipping cream into saucepan; cook over low heat until bubbles form around edge of pan. Place dark chocolate chips into separate bowl; pour hot whipping cream over top. Stir until melted and smooth. Set aside.
Cut cake into 8 heart shapes using medium-sized cookie cutter. Divide filling evenly among hearts; spread to cover top. Place 5 raspberries onto filling of 4 hearts; gently press into filling. Place 4 remaining hearts, filling-side down, onto raspberries. Spoon ganache over tops; allow to drip down sides.