1-Preheat the oven: Preheat the oven to 350°F (175°C) and line two muffin pans with cupcake liners.

2-Sift together dry ingredients: Sift together flour, baking powder, baking soda, and salt.

3-Dissolve coffee: Dissolve the instant coffee in hot coffee and allow to cool, then add milk.

4-Cream butter and sugars: In an electric mixer, cream the butter with granulated and brown sugars until pale and fluffy, about 5 minutes.

5-Add eggs and vanilla: Add eggs one at a time, beating well after each addition, then stir in vanilla extract.

6-Combine mixtures: Alternate adding half the flour mixture and half the milk mixture to the butter mixture, mixing until just combined; scrape bowl as needed.

7-Fill and bake: Fill cupcake liners two-thirds full and bake for 12-14 minutes until lightly golden and a toothpick inserted comes out clean.

8-Cool cupcakes: Cool cupcakes for 1-2 minutes in the pans before transferring to wire racks.

9-Whisk sugar and egg whites: Whisk sugar and egg whites over simmering water until warm and the sugar dissolves.

10-Beat meringue: Using an electric mixer, whisk on medium speed for 5 minutes, then increase to high and beat until stiff, glossy peaks form and the mixture cools, about 6 minutes.

11-Add butter: Reduce mixer speed, switch to paddle attachment, and add butter one piece at a time, beating well after each addition.

12-Finish frosting: Beat in vanilla extract and gently fold in caramel sauce.

13-Store frosting: Use immediately or refrigerate in an airtight container for up to one week.