Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper to prevent the cookies from sticking.
In a large mixing bowl, use an electric mixer to cream together the firm salted butter and granulated sugar until light and fluffy, about 2-3 minutes.
Add the seeds from the vanilla bean to the butter-sugar mixture. If using vanilla extract, add it now. Then, add the egg yolks one at a time, mixing until fully incorporated.
In a separate bowl, whisk together the all-purpose flour and a pinch of salt. Gradually add the dry mixture to the wet ingredients, mixing until just combined.
Using a spoon or cookie scoop, portion out the dough into equal-sized balls, about 1 inch in diameter. Roll each ball in the finely chopped pistachios.
Using your finger or a small measuring spoon, gently press down in the center of each cookie ball to create an indentation for the preserves.
Spoon a small amount of strawberry preserves into each indentation, being careful not to overfill.
Place the baking sheet in the preheated oven and bake for 15-18 minutes, or until the edges are lightly golden. Allow to cool on the baking sheet for a few minutes before transferring to a wire rack.
Once cooled, melt the chocolate in a double boiler or microwave. Drizzle the melted chocolate over the cooled cookies.
