Use whisk attachment to beat cold heavy cream and 3 tbsp of sugar in the cold bowl, until stiff peaks appear. Put whipped cream in the refrigerator until ready to use.
Heat up water in a double boiler over medium heat and lower heat to medium-low. Add egg yolks and 1/2 cup of sugar and gently whisk to mix. Cook yolks and sugar in the double boiler over medium-low heat, slowly stirring the whole time, for 7-10 minutes. (Until eggs are 160°-165° F.) Take off heat.
Add Amaretto and beat egg yolks with a whisk attachment on the immersion blender or hand held mixer. Beat until thickened and light in color.
Beat in mascarpone cheese until combined.
Carefully fold in whipped cream until all smooth.
Putting Together Tiramisu:
Use an 8x8 baking dish to put together Tiramisu.
Pour cold espresso into a bowl that will fit the lady finger cookies. Slowly dip each cookie in cold espresso but don't soak them. Lay dipped cookie in the corner of the dish. Repeat with each cookie, laying dipped cookies side by side until the bowl bottom of the dish is covered.
Cover cookie layer with half of mascarpone cream mixture, making sure it even all over.
Layer remaining espresso dipped cookies over the cream and cover with remaining mascarpone cream.
Dust with cocoa powder on top, cover the dish with plastic wrap and refrigerate overnight. (Or for at least 6 hours.)