Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a small bowl, combine the instant coffee granules with your chosen milk, stirring until fully dissolved.

In a large mixing bowl, beat the softened butter and sugar together until light and creamy, approximately 2-3 minutes.

Add the eggs, vanilla extract, and the dissolved coffee mixture to the creamed butter and sugar, mixing well.

In a separate bowl, sift together the gluten-free flour, baking powder, and salt. Gradually add this to the wet ingredients.

Spoon the batter into the prepared cupcake liners, filling each about 3/4 full.

Bake for 18-20 minutes or until springy to the touch and a toothpick inserted comes out clean.

Allow to cool in the tin for about 5 minutes, then transfer to a wire rack to cool completely.

Mix together the milk and instant coffee for the frosting. Beat softened butter until creamy, then add vanilla, milk/coffee mixture, and powdered sugar until fluffy.

Once cooled, generously frost each cupcake with the prepared frosting and garnish if desired.