In large mixing bowl at high speed, beat egg whites with cream of tartar until foamy. Add half of the sugar, 2 tablespoons at a time, beating constantly until sugar is dissolved and whites are glossy and stand in soft peaks. Rub just a bit of meringue between thumb and forefinger to feel if sugar has dissolved.
In small mixing bowl at high speed, beat egg yolks until thick and lemon-colored, about 3 to 5 minutes. Gradually beat in remaining sugar, water, vanilla and salt (if desired) until blended.
With a sifter or sprinkle flour with a sieve over whites. Add beaten yolk mixture. Gently, but thoroughly, fold yolk mixture and flour into whites.
Fill muffin cups 2/3 full. Bake in a preheated oven at 350 degrees for 10-15 min or until done.
In a small, heavy saucepan over high heat, combine the water, the remaining 1/2 cup confectioner’s sugar and the espresso or coffee powder. Bring to a boil, stirring occasionally. Remove from heat and let cool.
Use a fork to poke a few holes into cupcakes so that they will absorb liquid. Pour approximately ½-1 teaspoon of syrup onto each cupcake.
In a medium bowl using an electric mixer set on medium speed, beat together the mascarpone cheese, confectioner’s sugar and marsala until well blended. Add the cream and beat until fluffy, about 1 minute. Frost cupcakes with mascarpone/whipped cream mixture. Dust tops with cocoa powder (I used unsweetened) and then sprinkle with dark chocolate shavings.