Whisk eggs, 3 tablespoons milk, white sugar, and vanilla extract together in a shallow bowl until smooth.

Heat 1/4 inch of oil in a large saucepan over medium heat.

Dip 4 pieces of bread in egg mixture and fry until golden brown, about 2 minutes per side. Repeat with remaining pieces.

Combine 2 tablespoons of milk with custard powder in a small bowl; stir until smooth. Bring remaining milk to a boil in a small saucepan. Stir custard mixture into the saucepan. Reduce heat and cook, stirring frequently, until custard thickens, about 5 minutes.

Place 8 bread toasts on a shallow tray. Spread custard over each piece. Cover with remaining 8 toasts to form a sandwich. Dust with confectioners' sugar. Top each sandwich with a dollop of whipped cream and a strawberry. Insert a toothpick through the fruit to hold the sandwich together.