Heat oven to 325°. Line an 8-by-4-inch loaf pan with aluminum foil, leaving some extra foil along the sides of the pan to aid in lifting out the brownies. Grease the foil with soft butter. In a small bowl, whisk together the flour, salt, baking soda, and cocoa. Set aside.
Place the chocolate pieces and butter in the top of a double boiler over barely simmering water. When the chocolate has just melted, remove from heat. Whisk in the sugar, eggs, and vanilla. Whisk in the reserved flour mixture until just combined. Transfer mixture to the prepared pan. Bake for 25 to 30 minutes, or until a skewer inserted into the center of the pan comes out with a few moist crumbs attached. Cool on a rack at least 20 minutes.
Transfer the brownies to a cutting board. Using a 3 1/2-inch heart-shaped cookie cutter, cut out two heart shapes. Cover with plastic wrap until ready to assemble sundaes.
Spoon a few tablespoons of Raspberry Sauce onto each dessert plate. Place a brownie heart next to a scoop of strawberry ice cream. Serve.