Heat oven to 350 degrees.

Cream butter and sugar. Add egg and vanilla and mix well.

Add the rest of the flour and mix well. Dough will be soft.

Using a small (approximately 1 tsp.) cookie scoop, place dough 2 inches apart on a greased cookie sheet, or silicone or parchment-covered cookie sheet. Bake for 7 minutes.

While cookies are baking, cut the jumbo marshmallows in half using a pair or kitchen shears or regular scissors. After the cookies have baked for 7 minutes, remove them from the oven and place one cut marshmallow in the center of each cookie. Return the cookies to the oven for 3 more minutes. (The cookies will be baked for a total of 10 minutes).

Remove from the oven and let the cookies cool on the pan for about 10 minutes. Then transfer to a wire rack to cool completely.

While cookies are cooling, heat the heavy whipping cream on the stove to boiling. As soon as it boils, remove from the heat and add the chocolate chips. Let the chocolate chips sit in the hot cream for five minutes. Then stir until everything is smooth and glossy. Let cool slightly, then place a dollop on top of each cookie and spread as desired.