Preheat oven to 325 degrees F and adjust the oven rack to the lower third of the oven.
Grease a 9x5 inch loaf pan and line with parchment paper.
Measure out all ingredients, line them up and have them ready to go so the meringue doesn’t have to sit for too long.
Make Meringue First:
Beat egg whites until soft peaks form. Gradually beat in ½ cup sugar until stiff, glossy peaks form. Beat in vanilla, then fold in nut/chocolate mixture. Spread mixture over bottom and a little over halfway up the sides of the loaf pan, doing your best to make a nice cradle. Set it aside.
Sift the flour, then stir it together with the baking powder and salt; set aside.
Cream the butter and ½ cup granulated sugar until light and fluffy. Beat in egg yolks and vanilla and beat on high for a couple of minutes, scraping bowl often. Stir in flour mixture alternatively with milk until well blended (flour, milk, flour, milk, flour). Pour cake mixture into pan so it goes right down the center of the meringue cradle.
Bake in lower third of the oven for 45-50 minutes. Meringue will look golden. Do not invert pan yet. Let cool for about 5 minutes, then loosen with a spatula and set pan on a rack for 25 minutes. Invert on a serving plate. Peel off parchment paper; cool completely.