Preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper.
Put the baking chocolate in a microwave-safe bowl and melt it in the microwave. Stir and let cool.
In the bowl of an electric mixer, cream together the granulated sugar and butter until light and fluffy. With the mixer on low, slowly drizzle in the cooled chocolate. Scrape the bowl and mix again. Mix in the eggs one at a time, then add the buttermilk, food coloring and vanilla. Scrape the bowl and mix once more.
Combine the flour, baking powder and salt in a bowl and stir together. Add the flour mixture in 2 increments into the mixing bowl with the mixer on low. Scrape the bowl once and mix a final time until well combined. Fold in the chunked white chocolate.
Scoop generous tablespoons of the dough, roll in the confectioners' sugar until generously coated and transfer them to the prepared baking sheets. Bake until the cookies are poufy and set, about 12 minutes. Let them sit on the baking sheet for 1 to 2 minutes, then remove them to a wire rack to cool. Repeat with the remaining dough. Cool the cookies for 30 minutes and then recoat with confectioners' sugar if desired.