In a medium bowl, whisk together the flour, cacao powder and salt. Set aside.
In the bowl of a standing mixer, beat the butter and sugar on medium-high speed until smooth and creamy, about 3 minutes.
Add the vanilla bean paste and beat until combined.
Reduce speed to low and gradually add the flour mixture, beating until combined after each addition.
Finely chop half of the bittersweet chocolate discs and fold into the cookie dough by hand.
Turn the dough onto a cutting board and shape it into a 6-inch-long log. Wrap tightly in plastic wrap and freeze for 1 hour or until firm.
Preheat oven to 350 degrees. Line baking sheets with parchment paper.
Cut the dough into thin slices (no thicker than 1/4-inch). Using a cookie cutter, cut dough slices into heart shapes and place on prepared baking sheets.
Bake for 13 minutes. Transfer to wire racks and allow to cool completely.
In a double boiler, over medium-high heat, melt the remaining bittersweet chocolate discs, whisking until smooth.
Dip half of your heart-shaped cookie in the melted chocolate and return to parchment paper.
Sprinkle with sea salt and crumbled, freeze-dried raspberries. Allow to cool until chocolate is set.