Fudgy Brownie Heart Cake with Pink Whipped Cream

1 stick (8 tablespoons) unsalted butter

4 ounces fine-quality bittersweet chocolate (no more than 60% cacao if marked)

3/4 cup sugar

1 teaspoon pure vanilla extract

3 large eggs, beaten to blend

1/2 cup all-purpose flour

3 tablespoons unsweetened Dutch-process cocoa powder

1/2 teaspoon salt

For the cream:

1/2 cup cold heavy cream

1 tablespoon sugar

1/2 teaspoon raspberry extract

2 drops red food coloring

Garnish: fresh raspberries

Equipment: a 9-inch heart-shaped baking pan