Heat the oven to 350°F (175°C) and line a 12-cup muffin pan with paper liners. Whisk the flour, baking powder, and salt together in a medium bowl.

Beat the softened butter and granulated sugar for 2–3 minutes, until pale and fluffy. Add the eggs one at a time, then mix in the vanilla extract.

Add the dry ingredients in two or three additions, alternating with the room-temperature milk. Mix only until combined, taking care not to overmix.

Divide the batter evenly among the liners, filling each about two-thirds full. Bake for 18–22 minutes, until the tops spring back lightly and a toothpick comes out clean or with a few moist crumbs.

Cool the cupcakes in the pan for about 5 minutes, then transfer them to a wire rack. Let them cool completely before adding buttercream.

Beat the butter for the frosting until smooth, then gradually add the sifted confectioners’ sugar. Mix in the vanilla, salt, and enough cream or milk to make a smooth, pipeable buttercream.

Divide the buttercream and tint each portion with bright gel food coloring. Pipe tall swirls or deliberately uneven crooked shapes onto the cooled cupcakes.

Roll out the fondant and cut or mold small top hats, hatbands, teacups, clocks, playing-card shapes, and 10/6 labels. Place the decorations on the frosting just before serving.