For the cupcakes: Preheat oven to 325°F and prepare a cupcake pan with cupcake liners. Combine half of the sugar (6 tbsp | 78g), flour and salt and sift them together through a fine mesh sieve 5 times. Set aside.
Combine the egg whites, warm water, cream of tartar and vanilla extract and whip with a mixer on low speed until they get foamy. Increase speed to medium and continue whipping, adding remaining sugar 1 tablespoon at a time. Wait 5-10 seconds between each addition to give time for the sugar to incorporate. Increase to medium-high speed and whip until it reaches soft peaks.
Using a rubber spatula, gently fold the flour mixture into the egg whites a couple tablespoons at a time. Sift the flour mixture again as you add it to the egg whites. Repeat until all the flour mixture has been added. It’s important to add the flour mixture slowly to not deflate the egg whites.
Spoon the batter into the cupcake liners and fill 3/4 full – they should be pretty full. They rise better when more full. Bake the cupcakes until lightly browned, about 18-23 minutes. Remove cupcakes from the oven, then allow to cool completely on a wire rack. The cupcakes do fall a bit as they cool.
For the frosting: Whip together your cream, sugar and vanilla on medium-high speed. This pace will make it easier to avoid over-whipping or under-whipping the frosting.
Stop whipping as soon as the mixture becomes smooth and billowy. If you let the ingredients whip for too long, your frosting will curdle or take on a grainy texture. You want it to have a medium peak that forms when you lift up the whisk.
Pipe or spread the frosting onto the cupcakes and top with your desired decoration.
Topping ideas: Fruit: I love topping these cupcakes with fresh berries! Sprinkles: These treats look so cute with sprinkles on top. Candy: If you want even more sweetness to compliment these cupcakes, top them with crushed candy bars or your favorite bite-sized treat. Chocolate Curls: To add a touch of chocolatey goodness, try making these easy chocolate curls to sprinkle over the cupcakes.