Mix graham cracker crumbs, sugar, and melted butter in a bowl until well combined and the mixture sticks together when pressed.
Press the crumb mixture firmly into the bottom of a greased springform pan, creating an even crust that covers the base.
Bake the crust in a preheated oven at 180°C (350°F) for about 15 minutes until fragrant and golden. Remove and let cool completely.
While the crust cools, melt the dark chocolate in a saucepan over low heat, stirring until smooth and glossy.
In a separate bowl, beat the peanut butter, sugar, eggs, and vanilla until creamy and slightly fluffy.
Gradually fold the melted chocolate into the peanut butter mixture until fully incorporated and smooth.
Pour the chocolate-peanut butter filling over the cooled crust, spreading it evenly with a spatula.
Chill the tart in the refrigerator for at least 2 hours until set and glossy.
Before serving, sprinkle a pinch of sea salt on top for a savory contrast and enhance the flavors.
Slice the tart and enjoy the rich, luscious layers with a glass of milk or coffee.