In a mixing bowl, add the flour, cocoa powder, baking soda, and salt. Whisk together.

In a larger mixing bowl, add the butter and 1 1/4 cups of sugar and beat with an electric mixer at medium high speed until light and fluffy.

Add the egg, corn syrup, and vanilla, beat until well mixed.

Add the flour mixture to the wet mixture, use a heavy spoon and mix together. The dough comes together quickly. Cover and place in the fridge for 15 minutes or until the dough is firm enough to shape into balls.

When the dough is ready, place the remaining 1/4 cup of sugar in a small bowl. Shape dough into 1 inch balls, roll in sugar, and place 3 inches apart on baking sheet. (This was my 2nd sheet before going into the oven, I missed the photo from the first sheet.)

Bake 10-11 minutes or until set. Cool on the sheets for 3 minutes. (This is the 1st sheet that went into the oven, I missed taking the before photo with this sheet and took that photo with the second sheet.)

Then transfer to wire racks to cool completely.

Place 1 cookie upside down on a microwave safe plate. Place the flat end of a marshmallow on top.

Microwave on high for about 8-10 seconds or until the marshmallow is softened, it will expand when it is hot and soft, remove from microwave and quickly place another cookie on top, bottom side down, press down to make a sandwich cookie. Set aside to cool.

Repeat with remaining cookies and marshmallows.

Serve and enjoy.