Preheat your oven to 350F and grease a 6" round springform pan.

In a bowl, mix together the egg yolks, milk, and vanilla extract.

In a mixing bowl, sift together the flour, sugar, baking powder, and salt. Mix until combined.

Add the unsalted butter and mix on low speed until the flour is hydrated.

Slowly stream in the yolk mixture until combined. Scrape the bottom of the bowl to make sure all the ingredients are well combined.

Pour the batter into the prepared pan and bake for 30-35 minutes or until cooked through.

Let cool. Meanwhile, prepare the glaze by mixing the powdered sugar and milk together until smooth. Pour the glaze over the cooled cake and draw the number 5 on top.