Preheat oven to 350 F.
Grease the pan with butter.
With a hand held mixer beat eggs and sugar until mixture doubles in size, about 5-7 minutes. This is the most crucial step of the preparation. Since eggs act as leavening agent, it is important to beat until the mixture forms a ribbon when lifted from the beater.
Add butter, vanilla extract and beat for another couple of minutes.
Fold in flour until just combined.
Stir in cranberries until mixed.
Transfer batter to baking pan, spread the batter with a spoon or gently with clean hand as the batter is quite thick like cookie dough.
Bake in preheated oven for 40-50 minutes or until toothpick inserted in the center of the cake comes out clean.
For two third recipe bake time for my cake was 43 minutes in a nonstick pan and 38-39 minutes for one third recipe in a pyrex dish.
Let the cake cool completely before cutting into small pieces.
Serve it as it is for dessert or as a tea time snack. One can also serve it with some ice-cream or whipped cream, though I prefer without it.