In a large bowl, beat egg yolks and sugar until light colored and fluffy.  Add slightly cooled milk, lemon extract, lemon zest and melted butter.  Beat until well blended.
Sift together 2-1/4c of all purpose flour and 2 tsp baking powder.  Fold into egg mixture.
Grease two 9 inch round cake pans.  Line the bottom with parchment paper.
Pour batter into pans, dividing it evenly between the two.  Bake at 350 degrees Fahrenheit for 30 to 35 minutes.   Cakes are done when a skewer inserted into the center comes out clean.  Remove from oven and cool on racks.
This is delicious with jam spread between the layers and sprinkled with powdered sugar.  Or you can ice with your favorite icing.

Note: I bake it in a 9x13x2 inch pan.

The individual layers can also be frozen for future use.   Some day when you need a quick dessert, take one out of the freezer early in the day and then come time for dessert, slice and top with strawberries or ice cream (or both.)
 
Even if you are not in the habit of making Angel Food cakes, perhaps you have leftover yolks from making Egg-White Omelets or meringue.   Simply freeze the yolks and when you have enough, defrost in the fridge, bring to room temperature and then use them in making this wonderful Lemony Butter Sponge Cake.