Preheat oven to 350 degrees. Grease and flour 2 - 9 inch cake pans.
Sift together the flour and baking powder. In the bowl of an electric mixer, with the paddle attachment cream together the butter and sugar. Beat in the egg yolks, one at a time. Add the vanilla and continue to mix until light and fluffy. Scrape down the sides of the bowl. Reduce mixer speed to low and add the flour-baking powder mixture, alternating with the milk, beginning and ending with the flour. Continue to beat until combined. Do not over beat or your cake will be tough.
Pour batter into a greased and floured baking pan.
Bake at 350°F for 40 minutes.
Cool cake completely before frosting.Coffee Frosting: 2 sticks unsalted butter 5 tbsp sugar 5 egg yolks 1 cup, triple strength coffee, cooled pinch salt unsweetened cocoa powder for dusting I start by brewing a cup of 3 rounded teaspoons of instant coffee (I use Folgers) in 6 ounces boiling water. Let coffee cool. In a medium saucepan combine the cooled coffee, sugar, egg yolks and salt and heat to just before boiling, stirring constantly. Set aside and allow to cool. In the bowl of an electric mixer, cream the butter until smooth. Add the coffee mixture and continue to mix until light and fluffy....don't panic, it takes a long time to start to fluff.....about 10 minutes or more, but once it fluffs it really fluffs! Frost bottom layer and center of cake...dusting with unsweetened cocoa powder after frosting. Set the top layer on and finish frosting entire cake and dust with cocoa powder. That's my cake....it is my favorite and was first baked by Grandmother when she was newly married, I added the cocoa powder. I hope you enjoy it as much as my family has. Enjoy!