Preheat your oven to 350 °F (175 °C) and line a 12-cup muffin pan with bright blue paper liners.

In a medium bowl, whisk together the all-purpose flour, natural cocoa powder, baking powder, baking soda, and fine salt until evenly combined.

Using a mixer on medium speed, beat the softened unsalted butter with granulated sugar and light brown sugar until pale and fluffy, about 2 minutes.

Incorporate the eggs one at a time into the butter-sugar mixture, scraping down the sides of the bowl after each addition, then mix in the pure vanilla extract thoroughly.

Alternately add the dry ingredients and whole milk to the wet ingredients in three parts, beginning and ending with the dry ingredients. Stir gently until no flour streaks remain, taking care not to overmix.

Evenly divide the batter among the lined muffin cups, filling each about two-thirds full. Bake for 18 minutes or until a toothpick inserted into the center comes out clean. Let the muffins cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

Beat softened butter until smooth. Gradually add sifted powdered sugar, about 1 cup at a time, on low speed.

Blend in vanilla extract, a pinch of salt, and enough heavy cream or milk to achieve a thick but pipeable texture. Increase mixer speed to medium-high and whip for 1 minute to lighten the frosting.

Fit a piping bag with a large round tip and pipe two stacked concentric circles of buttercream on each cooled cupcake.

Press two dark chocolate nonpareils into each marshmallow to form eyes. Arrange five nonpareils in a curved shape for the mouth. Insert an orange candy-coated chocolate or small candy corn piece halfway into the center to act as the nose.

Place the decorated marshmallow atop each buttercream snow pile. Insert two halved mini pretzel sticks at slight upward angles into the frosting for the snowman’s arms. Press three regular chocolate chips vertically down the front of the buttercream as buttons.

Display the snowman cupcakes on a cool platter. Store covered at room temperature for up to 2 days or refrigerate for up to 4 days; bring to room temperature before serving.