Preheat the oven to 350°F (175°C).
In a mixing bowl, cream together softened butter and sugar until light and fluffy.
Add in the egg, food coloring, and vanilla extract; beat until well combined.
In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt.
Gradually add the dry mixture to the wet ingredients, mixing until just combined.
Chill the dough for at least 30 minutes.
Scoop tablespoon-sized portions of dough and roll them into balls.
Place the dough balls on a lined baking sheet and make an indentation in the center of each with your thumb.
Fill each thumbprint with your chosen jam or preserves.
Bake for 10-12 minutes, until the edges are set but the centers are still soft.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.
