Vaselopita is a traditional Greek New Year's Day cake—whoever finds the coin hidden within the cake will have good luck for the next year.
Preheat the oven to 350 degrees F (175 degrees C). Generously grease a round 10-inch cake pan.
In a medium bowl, cream butter and 2 cups sugar until light; add flour and stir until mixture is mealy. Add eggs one at a time, beating well after each egg.
Stir baking powder into milk then stir into flour mixture. Mix soda and lemon juice; stir into batter. Pour batter into the greased pan.
Bake in the preheated oven for 20 minutes. Sprinkle with nuts and 1 tablespoon white sugar, then return to oven for 20 to 30 minutes longer, until a toothpick inserted in center comes out clean.
Remove cake from the oven and gently cut a small hole in the middle. Place a quarter in the hole; cover the hole with powdered sugar. Cool cake on a rack for about 10 minutes. Invert cake onto a serving dish. Sift powdered over the top and serve warm.