In a medium saucepan, whisk together 2 cups of whole milk, 1/2 cup of granulated sugar, 1/4 cup of cornstarch, and 4 egg yolks until smooth. Place over medium heat, stirring continuously for about 6 to 8 minutes until thickened. Remove from heat, stir in 2 tablespoons of butter and 1 teaspoon of vanilla extract, cover with plastic wrap, and chill for at least 1 hour.

In a large bowl, combine 1 ½ cups of all-purpose flour, 2 tablespoons of sugar, 2 teaspoons of baking powder, and a pinch of salt. Whisk until evenly mixed.

In a separate bowl, whisk together 1 cup of whole milk, 1 large egg, 2 tablespoons of melted butter, and 1 teaspoon of vanilla extract. Slowly pour into the dry mixture and gently stir until just combined.

Heat a nonstick skillet over medium heat and brush with melted butter. Pour about 1/4 cup of batter for each pancake, cooking for about 2-3 minutes on one side until bubbles form. Flip and cook for an additional 1-2 minutes until golden brown.

Take two pancakes and place a spoonful of chilled custard filling between them. Dust with powdered sugar or drizzle with maple syrup, and garnish with berries if desired.