Gather the ingredients. Allow the butter and egg to come up to nearly room temperature. Preheat the oven to 350°F. Line your cookie sheets with parchment paper.

Drain the maraschino cherries, but save the juice!

Whisk the flour and cocoa together in a bowl.

Use a hand-held mixer to beat the butter until a little creamy (about 45 seconds).

Add the sugar, baking powder, baking soda, and salt. Beat until well combined.

Add the egg and vanilla and beat until very smooth.

Add the flour mixture in thirds, mixing after each addition. Mix until a thick dough forms, but do not overmix. You can place the dough in the fridge to chill if it is too sticky to work with.

Make the fudgy frosting. In a saucepan, combine the sweetened condensed milk with the chocolate pieces.

Melt the chocolate and condensed milk over low heat, stirring constantly. The mixture will become thick. As soon as everything is melted, remove the pot from the heat. Add 2 teaspoons of the reserved maraschino cherry juice, and stir well. If the mixture is still far too thick to work with, continue adding the cherry juice 1 teaspoon at a time until you reach a spreadable consistency.

Form 1 inch diameter balls of dough, and place them approximately 2 inches apart on an ungreased cookie sheet.

Use your thumb to create an indentation in each of the balls. To be more consistent, I used the melon baller tool, and then used a damp finger to press down the little nub that formed from the tool’s hole.

Place a maraschino cherry into each of the indents, then spread the fudgy chocolate frosting over the top of the cookie so that the cherry is completely covered.

Bake in the preheated oven for 10 to 12 minutes. Rotate the sheets halfway through baking time. Allow the cookies to cool on the cookie sheet for approximately five minutes before transferring them to a metal rack to cool completely. Store the cookies in an airtight container for up to five days.