In a large mixing bowl, whisk together flour, salt, baking powder, and Dutch cocoa powder until well combined.

In another bowl, cream the softened unsalted butter with granulated and brown sugar until light and fluffy, about 3-4 minutes.

Beat in egg, vanilla extract, and white vinegar until fully incorporated.

Gradually mix the dry ingredients into the wet mixture until just combined.

Stir in gel red food coloring until dough is uniformly vibrant.

Cover the mixing bowl with plastic wrap and refrigerate the dough for about 1 hour.

Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Scoop out 2 tablespoons for each cookie, flatten a ball, create a well, spoon in marshmallow fluff, fold and roll back into ball.

Bake the cookies for 12-15 minutes or until edges are set and centers are slightly soft.

Let the cookies cool on the baking sheet for about 5 minutes before transferring to a wire rack.

Optionally, drizzle melted white chocolate over the cookies after they have cooled.