Fudgy Filled Cupcakes

Preheat the oven to 350 degrees F (175 degrees C). Line 30 muffin cups with paper or foil liners.

Mix cream cheese, sugar, and egg together in a small bowl for the filling. Fold in chocolate chips; set aside.

Place butter, chocolate chips, and vanilla extract for the cupcakes in the top of a double boiler over simmering water. Stir frequently, scraping down the sides with a rubber spatula to avoid scorching, until chocolate is melted and mixture is smooth, about 5 minutes. Remove from the heat and allow to cool slightly.

Beat eggs in a large bowl with a whisk or an electric mixer until frothy. Beat in sugar gradually until it dissolves. Slowly beat in flour. Fold in the cooled chocolate mixture. Fill the prepared cupcake liners 1/3 full with chocolate batter. Drop a heaping teaspoon of filling onto each cupcake, then cover with a generous spoonful of batter.

Bake in the preheated oven until tops spring back when lightly pressed, 25 to 30 minutes. Cool in the tins for 5 minutes before transferring to a wire rack to cool completely.